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EFFECTIVE

• Dyspepsia. Oral calcium carbonate is approved by the US Food and Drug Administration (FDA) as an antacid. Details: Taking calcium carbonate orally as an antacid is effective for treating dyspepsia (1843). Calcium carbonate has FDA approval as an antacid.
• Hyperkalemia. Intravenous calcium gluconate is approved by the US Food and Drug Administration (FDA) for preventing hyperkalemia-induced cardiac abnormalities. Details: Administering calcium gluconate intravenously can reverse electrocardiographic changes and arrhythmias induced by hyperkalemia (12946). Intravenous calcium gluconate is FDA-approved for preventing hyperkalemia-induced cardiac abnormalities.
• Hypocalcemia. Oral calcium treats and prevents hypocalcemia. Intravenous calcium is used to treat severe hypocalcemia. Details: Taking calcium orally is effective for treating and preventing hypocalcemia. Intravenous calcium gluconate, acetate, gluceptate, or chloride is effective for severe hypocalcemia or hypocalcemic tetany (12928).
• Kidney failure. Oral calcium carbonate or calcium acetate is used as a phosphate binder during kidney failure. Details: Taking calcium carbonate or calcium acetate orally is effective as a phosphate binder. Calcium acetate (PhosLo) appears to control hyperphosphatemia better than sevelamer (Renagel) (12943,12944,38990). Calcium citrate is not recommended for this purpose because it increases aluminum absorption and does not bind phosphate as efficiently as calcium acetate or calcium carbonate (21631). Some clinical research also shows that taking calcium orally reduces blood pressure in patients with kidney failure (975).

LIKELY EFFECTIVE

• Corticosteroid-induced osteoporosis. Oral calcium in combination with vitamin D prevents bone density loss that occurs during long-term treatment with corticosteroids. Details: Taking calcium in combination with vitamin D as adjunctive therapy seems to be effective for reducing bone mineral density loss in people using corticosteroids long-term (982,1046,1830,1831,1832,4462,4463,4464,4465,4466)(4467,12945,38493). One specific product used in clinical research is Oscal (Marion Merrel Dow Inc.), which contains elemental calcium 500 mg per tablet plus vitamin D 125 IU per tablet (982). Another product used is Oscal 250 + D (SmithKline Beecham Healthcare), which contains elemental calcium 250 mg and vitamin D 125 IU per tablet (1046).
• Hyperparathyroidism. Oral calcium reduces parathyroid hormone levels in patients with secondary hyperparathyroidism due to kidney failure. Details: Taking calcium orally reduces parathyroid hormone levels in patients with kidney failure and secondary hyperparathyroidism (1827,1828,1829,39174,39425). In elderly women, the combination of calcium and vitamin D reverses secondary hyperparathyroidism and reduces hip fracture risk (8818). Also, population research suggests increased calcium intake from the diet and supplements reduces the risk of primary hyperparathyroidism in women. Supplemental intakes of at least 500 mg/day and dietary intakes of approximately 1100 mg/day are considered to be protective (91353).
• Osteoporosis. Adequate calcium intake, from the diet and/or supplements, is recommended for the prevention and treatment of osteoporosis. Details: The Bone Health and Osteoporosis Foundation (BHOF) recommends ensuring adequate calcium intake in line with the recommended dietary allowance (RDA) by age, along with adequate vitamin D intake, for the prevention and treatment of osteoporosis in adults over 50 years of age. Supplementation can be used to augment dietary intake when adequate dietary intake is not feasible (109425). In the US and Canada, foods containing at least 200 mg calcium with less phosphorous content than calcium can be labelled with a health claim regarding the relationship between adequate calcium intake and a reduced risk for osteoporosis (11940,102148). However, calcium supplementation is not recommended specifically for the primary prevention of osteoporosis. The US Preventive Task Force (USPSTF) states that the current evidence is insufficient to assess the balance of benefits and harms of vitamin D and calcium supplementation, alone or in combination, for the primary prevention of fractures in community dwelling adults without osteoporosis (95695). Also, calcium supplements do not seem to be effective for preventing loss of bone mineral density (BMD) during lactation (988), in patients who have had bone marrow transplantation (1817), or in patients who have had renal transplantation (4823,38736,38871). Maximal bone growth occurs in the teenage years, and then BMD in females remains relatively constant until age 30-40. After age 40, bone loss typically occurs at rates of 0.5% to 1% per year. In males, this occurs several decades later. Bone loss is more pronounced if dietary calcium intake is below the RDA, which is the case for many Americans (2571,2578). One meta-analysis of randomized controlled trials in healthy children 7-14 years old shows that fortifying food with calcium 250-1000 mg daily for up to 24 months modestly improves femoral neck BMD, but not hip or spine BMD. However, the included trials did not supplement vitamin D (107232). During the 5 years immediately after menopause, calcium supplementation has very little effect on bone loss (2569,2570,2575,2576). The rapid loss of estrogen causes a high bone resorption rate, which increases serum calcium levels and therefore decreases intestinal absorption of calcium (2570). After this period, the typical rate of bone loss is 2% per year (2572,2576). Taking calcium 1000-1600 mg daily as carbonate, citrate, lactate gluconate, or citrate malate salt decreases this rate by 0.25% to 1% annually (977,979,981,2569,2571,2572,2575,2576,2578,6850)(38978,38980,39064). The greatest reductions (1% or more) are seen in the first 1-2 years of supplementation when bone remodeling foci can be filled (2569,2576). After this period, the differences in rate of loss between supplemented and non-supplemented females are closer to 0.25% per year (2569,2577). A meta-analysis of clinical evidence suggests that there is no additional benefit after 4 years (38980). Small clinical studies have found that continuous calcium supplementation at an average daily dose of 1050 mg, started after menopause and continued for 1.5-4 years, may reduce fracture rates by 26% when compared with no calcium supplementation. The largest of these studies was conducted in nursing home residents who also received daily vitamin D; the benefits of calcium, specifically, are unclear (39386). Some research also suggests that calcium and vitamin D improves primary prevention of osteoporotic fractures in some older individuals with osteoporosis, particularly the elderly and those who are no longer community dwelling (12930,38875,38849,39026,109471). However, not all research is positive. One large clinical trial in elderly adults with a low-trauma fracture show that taking calcium 1000 mg daily with or without vitamin D 800 IU daily for 2-7 years does not reduce the risk of a second fracture when compared with placebo (13073). Another clinical study shows that taking calcium 1000 mg daily plus vitamin D 800 IU daily does not prevent a second fracture in elderly patients, or prevent a first fracture in elderly patients with other risk factors such as low body weight (less than 58 kg, 127.6 pounds), smoking, family history of hip fracture, or fair or poor self-reported health (12929). Also, some exploratory research suggests that supplements may need to be continued indefinitely; in adults over 68 years of age, any effects of 2 years of calcium supplements on BMD appear to be lost within 2 years after discontinuing supplements (6853). Calcium has additive effects when used with other agents such as vitamin D, estrogens, or calcitonin. Whereas calcium alone generally reduces or prevents loss of BMD, combination with other agents can produce small increases in BMD ranging from 0.3% to 3.3% depending on the combination and dosages used (978,980,1836,2570,2571,2572,2576). However, one meta-analysis in healthy adults shows that fortifying foods with calcium 250-1000 mg daily, in conjunction with vitamin D supplementation, for up to 24 months does not improve BMD when compared with control (107232). The full potential of osteoporosis treatments cannot be realized without adequate calcium intake (2569,2570,2571,2572). Advise patients taking agents such as estrogens, calcitonin, bisphosphonates, or raloxifene (Evista) to ensure that their daily calcium intake meets the RDA. Use supplements if necessary. The usefulness of calcium in preventing osteoporosis in males is not as well-studied. Some observational research has found that calcium 870 mg daily is not associated with changes in BMD and bone loss in males (97201). However, clinical evidence suggests that taking calcium 1000 mg daily for 2 years might improve trabecular or cortical bone mass by 2% to 4% (980,8827,8873). Dietary supplementation with calcium and vitamin D seems to moderately reduce bone loss measured in the femoral neck, spine, and total body, and seems to reduce the incidence of nonvertebral fractures in older patients with osteopenia or low BMD (980).
• Premenstrual syndrome (PMS). Adequate calcium intake seems to prevent symptoms of PMS. Details: There seems to be a link between low dietary calcium intake and symptoms of PMS (2004,6847,39007). Taking calcium 1000-1336 mg daily seems to significantly reduce depressed mood, water retention, and pain, especially if daily calcium intake is inadequate (1822,1823,1824,2004,95821). Calcium carbonate 1200 mg daily seems to decrease PMS symptom scores by about 18% when compared with placebo (1822). Increasing dietary calcium intake is also associated with a decreased risk of developing PMS. Consuming an average of 1283 mg of calcium per day from foods is associated with about a 30% lower risk of developing PMS compared with consuming an average of 529 mg daily (13094); however, taking calcium supplements does not appear to be associated with the risk of developing PMS.

POSSIBLY EFFECTIVE

• Colorectal cancer. Oral calcium seems to be beneficial for preventing colorectal cancer, especially in those with adequate vitamin D levels and normal body mass index (BMI). Details: Population studies have found that increased intake of dietary or supplemental calcium is associated with a reduced risk of colorectal cancer and colorectal adenomas (1047,8820,12120,38951,98898,98899). Clinical trials and meta-analyses of clinical research also show that taking calcium supplements 1.2-2 grams daily for up to 4 years can reduce the risk of colorectal adenoma recurrence by up to 29% (970,12118,12950,15267,34596,38718,39042,95817). However, not all research has been positive. Some meta-analyses of clinical research or observational studies suggest that taking calcium does not reduce the risk of familial adenomatous polyposis or colorectal cancer (34596,39042,39349). Other contradictory research suggests that postmenopausal females who take calcium 1000 mg daily plus vitamin D 400 IU daily do not have a reduced risk of developing colorectal cancer (14290); however, this finding may not be reliable due to the high baseline intake of calcium in study participants. The reason for these conflicting findings is not entirely clear. Vitamin D might be an important factor. People with lower than average vitamin D levels do not seem to get any benefit from calcium supplements (12118). Also, one meta-analysis of previous trials suggests that taking calcium 1200 mg daily reduces the risk of colorectal adenomas in people with a normal BMI, but not in those who are overweight or obese (99715). Despite this conflicting evidence, the US Food and Drug Administration (FDA) approved a qualified health claim in 2005 stating that calcium supplements may reduce the risk of colorectal cancer and colorectal adenomas. However, the FDA has determined that there is little scientific evidence to support this claim (102366).
• Fetal bone mineralization. If calcium intakes are low during pregnancy, oral calcium seems to be beneficial for increasing fetal bone density. Details: With low dietary calcium intake (less than 562 mg elemental calcium daily) during pregnancy, calcium supplementation increases fetal bone mineralization and density. However, calcium supplementation does not offer any additional benefit if calcium intakes are adequate (3263,3264).
• Hypertension. Oral calcium seems to reduce blood pressure by a small amount. However, it is unclear if this reduction is clinically significant. Details: Many clinical trials and observational studies show that intake of calcium supplements or dietary calcium modestly reduces blood pressure in patients with or without hypertension, usually around 1-2 mmHg. Calcium seems to be more effective for certain subpopulations of patients, such as salt-sensitive people and patients with low baseline dietary calcium intake (945,972,974,976,984,1818,1819,1820,1821,6852)(13138,14406,38803,39063,39094,39221). Also, a meta-analysis of clinical research shows that calcium intake during pregnancy reduces systolic blood pressure in offspring by 1-2 mmHg (38852). However, a large-scale clinical trial in postmenopausal females shows that taking vitamin D (cholecalciferol) 400 IU daily in combination with elemental calcium 1000 mg daily does not lower blood pressure or reduce the risk of developing hypertension (16714). Additionally, a meta-analysis of 8 clinical trials shows that taking calcium in combination with vitamin D for up to 7 years has no effect on blood pressure (98861). The validity of this finding is limited by the poor methodological quality of the included studies. Some observational research suggests that calcium can reduce the risk for hypertension. Population research in females aged 45 years and older suggests that higher intake of calcium from both diet and supplement sources is linked to a lower risk of developing hypertension when compared to lower calcium intake (14265). In 2005, the US Food and Drug Administration (FDA) approved a qualified health claim stating that calcium supplements may reduce the risk of hypertension. However, the FDA has concluded that this claim is based on supporting, rather than conclusive, evidence (102367).
• Osteomalacia. Oral calcium seems to reverse osteomalacia caused by very low calcium intakes. Details: Osteomalacia is commonly caused by vitamin D deficiency; however, very low calcium intake can also lead to osteomalacia in children and adults. Calcium supplementation can reverse osteomalacia caused by calcium deficiency. Along with appropriate vitamin D supplementation, individuals at risk of osteomalacia need sufficient calcium intake (94819).
• Pre-eclampsia. Oral calcium seems to reduce the risk of pre-eclampsia in high risk pregnancies, especially if calcium intakes are low. Details: Although there is some conflicting evidence (971,38756), most clinical research shows that taking calcium orally 1-2 grams daily reduces pregnancy-related hypertension and pre-eclampsia (973,1833,8828,39043,39319,39426,96480). Calcium appears to reduce the risk of pre-eclampsia by about 50% when compared with placebo. One meta-analysis of 19 controlled trials involving over 29,000 pregnancies found that for every 19 females treated with calcium, one episode of pre-eclampsia would be avoided (96480). Calcium appears to have the greatest effect in individuals at high-risk of pre-eclampsia or with low calcium levels, and when taken at greater than or equal to 20 weeks of gestation (15029,38497,96480,99714). In 2005, the US Food and Drug Administration (FDA) approved a qualified health claim regarding the use of calcium supplements to reduce the risk of pregnancy-induced hypertension and pre-eclampsia. However, due to the limited and conflicting research available at that time, the FDA stated that this outcome was highly unlikely. Since then, large, high-quality clinical research has supported this finding. In fact, in 2016 the World Health Organization (WHO) released a recommendation to prescribe oral calcium supplementation 1.5-2 grams daily during pregnancies at high risk of pre-eclampsia if dietary calcium intakes are low, in order to prevent pre-eclampsia (97347).
• Rickets. Oral calcium seems to reverse rickets caused by very low calcium intakes. Details: Rickets is commonly caused be vitamin D deficiency; however, very low calcium intake can also lead to rickets. Calcium supplementation can reverse rickets caused by calcium deficiency (94819). A small clinical study in children with nutritional rickets shows that taking calcium 500-2000 mg daily for 24 weeks improves radiographically measured rickets caused by calcium deficiency. Rickets seems to improve more rapidly with calcium 1000 mg compared to calcium 500 mg. However, increasing the calcium dose to 2000 mg daily is not more beneficial than calcium 1000 mg daily (98904).
• Tooth retention. Oral calcium with vitamin D seems to help with tooth retention in the elderly population. Details: A clinical trial in the elderly population shows that taking calcium citrate malate 500 mg daily along with vitamin D3 (cholecalciferol) 700 IU daily orally for 3 years reduces the risk of tooth loss by about 52% when compared with placebo (8816).

POSSIBLY INEFFECTIVE

• Breast cancer. Oral calcium does not seem to be beneficial for breast cancer prevention. Details: Although some population research disagrees (15631,39041,95811,107237), most research shows that increased calcium intake is not associated with a reduced risk of breast cancer (15631,16715,98895,107236,107237). Subgroup analyses of population research suggest that calcium intake may reduce the risk of breast cancer in postmenopausal, but not pre-menopausal, adults (15631,107237). Another subgroup analysis in a large meta-analysis of population research also suggests that dietary intake may reduce estrogen receptor(ER)-negative breast cancer, but not ER-positive breast cancer (107236). However, most other research has not evaluated the effects of calcium supplementation or intake on breast cancer subtypes. The best evidence to date, from a large scale clinical trial (Women's Health Initiative), shows that taking vitamin D (cholecalciferol) 400 IU daily plus calcium 1000 mg daily for 7 years after menopause does not reduce the risk of developing invasive breast cancer at the end of the study and 5 years after the end of the intervention (16715,98895).
• Fractures. Although oral calcium prevents fractures in osteoporosis, most evidence shows that calcium does NOT prevent factures in people who do not have osteoporosis. See Osteoporosis discussion for more information on the use of calcium for this purpose. Details: The most recent and robust meta-analysis of clinical research shows that calcium supplementation with or without vitamin D is NOT associated with reduced fractures in older adults without osteoporosis (95822). A large-scale study in postmenopausal females aged 50-79 years suggests calcium 1000 mg plus vitamin D 400 IU daily for 7 years only modestly improves bone mineral density (BMD) and does not significantly reduce fracture risk. This lack of effect may have been due to low adherence to the treatment regimen. In those who were 80% adherent, the combination of calcium plus vitamin D reduced the risk of hip fracture by about 29% (14282). Also, some clinical research shows that taking calcium carbonate 1000 mg and vitamin D 400 IU for 5 years does not attenuate loss of height after menopause when compared with placebo (95810). Additional meta-analyses of clinical and observational evidence suggest that calcium supplementation is not associated with a reduced risk of vertebral or nonvertebral fractures, such as hip fractures (38589,38888,98895). Some other research has suggested that calcium in combination with vitamin D reduces fracture risk in older patients without osteoporosis (980,1836,8818,12930,12933,12952,38849,102145,107235); however, this research is confounded by a number of variables, including the presence of hormonal therapy and differing levels of fracture risk at baseline (1836,8818,95822). Conflicting findings on this topic might also be due to genetic differences in patient populations. A population analysis of the Women's Health Initiative study found that, in older females with the lowest genetic susceptibility to low bone mineral density (BMD), taking calcium with vitamin D is associated with a reduction in fracture risk. However, in females with a higher genetic susceptibility to low BMD, there is no association between supplementation and fracture risk. This might be because individuals with a lower susceptibility to low BMD are also more responsive to calcium and vitamin D supplementation (97357). As of April 2018, the U.S. Preventative Services Task Force (USPSTF) concludes that there is insufficient evidence to determine whether supplementing with vitamin D >400 IU daily along with calcium >1000 mg daily is safe and effective for preventing fractures in community dwelling adults without vitamin D deficiency, osteoporosis, or a history of fracture. USPSTF recommends against supplementing with calcium 1000 mg daily or less along with vitamin D 400 IU daily or less for preventing primary fractures in community-dwelling postmenopausal females (95695).
• Obesity. Oral calcium does not seem to improve weight loss. Details: Observational research has found that adults and children with low calcium intake are more likely to gain weight, have a higher body mass index (BMI), and be overweight or obese when compared to people with high calcium intake (12124,12125,12126,12127,14265). Additional observational research has found that increasing calcium intake is associated with weight loss in females; the results in males have been conflicting (12127,15602,15603). Despite these findings from observational research and a few small clinical studies (12128,15397,14438,98905), most clinical research has found that increased calcium intake does not increase weight loss (12052,13138,15396,15399,38985,39004,97356). The most recent meta-analysis of 20 clinical studies shows that daily dietary and supplemental calcium intake that meets the dietary reference intake (DRI) of 1000 mg or more daily does not increase weight loss in overweight individuals or patients with obesity when compared with intake below the DRI (95813). An older meta-analysis of 13 clinical trials also shows that increased dietary and supplemental calcium intake does not increase weight loss (15605).
• Overall mortality. Oral calcium does not seem to reduce overall mortality. Details: While some population research has found that calcium taken in combination with vitamin D in older females is associated with a lower risk of death (97353), most evidence shows that calcium, with or without vitamin D, has no effect on all-cause mortality (93533,97308).

INEFFECTIVE

• Cardiovascular disease (CVD). Oral calcium does not reduce the risk of developing CVD and may actually increase risk in some patients. Details: Clinical research shows that calcium does not decrease CVD risk. Several separate meta-analyses of clinical and population research involving over 50,000 patients show that taking calcium 600-1200 mg daily for up to 7 years does not reduce the risk of CVD-related outcomes, including stroke and myocardial infarction, cardiovascular death, or overall mortality (39018,91350,92994,93533,97308,98902,107231,107233). No association was found between total dietary or supplemental calcium intake with or without vitamin D and the risk of CVD or mortality (91350,93533,97308). In fact, some population and clinical research has found that when calcium is used alone or with vitamin D, there is an INCREASED risk of CVD and coronary heart disease (38077,107233). However, other clinical research disagrees (93533). One meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years increases the risk of CVD and coronary heart disease by 1.1-1.2 times when compared with control. However, the majority of the included research evaluated postmenopausal females and it is unclear if this finding is applicable to other populations (107233).
• Chemotherapy-induced peripheral neuropathy. Intravenous calcium does not prevent nerve pain in patients given oxaliplatin. Oral calcium has not been evaluated for this purpose. Details: While pooled analyses of cohort studies and randomized controlled trials suggest that calcium and magnesium infusion decreases the incidence of oxaliplatin-induced neurotoxicity, a meta-analysis of only randomized controlled trials shows that the infusion has no effect in preventing neurotoxicity (90028,90029,90031). Additionally, clinical trials show that administering calcium gluconate 1 gram with magnesium sulfate 1 gram intravenously immediately before, or before and after, the administration of a single oxaliplatin cycle (90005), or over the entire 6-cycle course of oxaliplatin, does not improve symptoms of neurotoxicity when compared with placebo (96474).
• Myocardial infarction (MI). Oral calcium does not prevent MI. When taken in the absence of vitamin D, oral calcium may increase the risk of MI. Details: Population research has found that increased dietary intake of calcium is associated with a decreased risk of MI (91350). However, a 2010 meta-analysis of clinical research shows that taking calcium at a dose of at least 500 mg daily is associated with an approximate 30% INCREASE in the risk of MI in patients over the age of 40. According to this analysis, one additional case of MI will occur for every 69 patients that take calcium for 5 years (17482). A more recent meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years increases the risk of MI by 1.2 times when compared with control. However, the majority of the included research studied postmenopausal females and it is unclear if this finding is applicable to other populations (107233) In contrast, other meta-analyses of clinical research have shown that taking calcium for up to 7 years is NOT associated with an increased risk of MI, including a meta-analysis that only included postmenopausal females (93533,107231). Reasons for these discrepancies are not entirely clear. It may relate to whether calcium is taken as monotherapy or in combination with vitamin D. When taken with vitamin D, which is commonly recommended, calcium supplementation does not appear to be associated with an increased risk of MI in postmenopausal females (93533). Also, the association between calcium supplementation and MI risk may be influenced by the amount of calcium consumed as part of the diet. Supplementation with calcium may be associated with an increased risk of MI in people with dietary calcium intake above 805 mg daily, but not in those with dietary calcium intake below 805 mg daily (17482)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Alcohol use disorder. It is unclear if oral calcium is beneficial for alcohol use disorder. Details: Preliminary clinical research shows that taking calcium carbonate 800 mg and vitamin D 200 IU orally daily for 14 days modestly reduces alcohol craving scores and withdrawal scores when compared with placebo in adults with alcohol dependence that are undergoing withdrawal. Taking calcium carbonate did not reduce the need for diazepam; however, the study may have been inadequately powered to detect a difference between groups (107234).
• Atherosclerosis. It is unclear if oral calcium is beneficial for atherosclerosis. Details: A population study has found that taking calcium 1.2 grams daily for 3 years has no effect on carotid intima thickness or carotid atherosclerosis incidence. A total calcium intake (dietary and supplemental) of at least 1794 mg daily in older females may be associated with a decreased risk of carotid atherosclerosis when compared with a total calcium intake below 1010 mg daily (97351).
• Autism spectrum disorder. It is unclear if oral calcium during pregnancy is beneficial for reducing the odds of autism spectrum disorder in the offspring. Details: A small observational study found that calcium supplementation during pregnancy is associated with a 52% reduced odds of an autism spectrum disorder in the offspring (98900).
• Cancer. Oral calcium alone does not seem to prevent cancer. It is unclear if oral calcium with vitamin D is beneficial for preventing cancer. Details: Taking calcium alone does not seem to significantly reduce the risk of cancer (12118,15629). The role of calcium in cancer prevention when taken along with vitamin D is controversial, as conflicting results exist. One clinical trial shows that healthy postmenopausal females who take supplemental calcium 1400-1500 mg daily plus vitamin D3 (cholecalciferol) 1100 IU daily have a 60% lower relative risk for developing cancer of any type. Approximately 25 postmenopausal females would need to take this combination for 4 years to prevent one occurrence of cancer (15629). However, a more recent clinical study shows that healthy postmenopausal females who take supplemental calcium 1500 mg daily plus vitamin D3 (cholecalciferol) 2000 IU daily do not have a reduced risk of cancer at 4 years (93943). Reasons for the disparate results are not entirely clear. The discrepancies do not appear to be related to baseline vitamin D levels or different study populations. It is possible that, given the 10-year time lapse between the two publications, the discrepancies result from differences in cancer detection capability. Also, since cancer risk was a secondary outcome measure in the earlier study and a primary outcome measure in the more recent study, it is possible that the discrepancies result from differences in statistical methodologies. The effect of vitamin D and calcium on cancer risk in males and younger patients is not known. There is also interest in using calcium for reducing the risk of hematological malignancies. An analysis of the Women's Health Initiative study shows that taking calcium 1000 mg daily in combination with vitamin D3 400 IU for up to 10 years is associated with a 20% reduction in the risk of hematologic malignancies when compared with placebo. However, no effect on hematologic malignancy related mortality was seen (97354).
• Depression. It is unclear if oral calcium is beneficial for depression prevention. Details: Population research has found no association between a higher dietary intake of calcium and the risk of depression when compared with a lower dietary intake of calcium (96480).
• Diabetes. It is unclear if oral calcium is beneficial for type 2 diabetes prevention. Details: Some population research has found that a higher intake of calcium from diet or supplements, alone or in combination with vitamin D, is associated with a lower risk of developing type 2 diabetes when compared with lower calcium intake (14265,16713,96473). However, population research is often limited by confounding variables. For example, one analysis found that any beneficial effect might be influenced by concomitant magnesium intake (96473). Furthermore, other population research has found that serum calcium levels higher than 9.6 mg/dL are associated with greater risk of developing diabetes in Chinese adults with osteoporosis. This study is limited because it was not determined whether increased serum calcium was due to increased calcium intake or another factor such as parathyroid function (95815).
• Dysmenorrhea. It is unclear if oral calcium is beneficial for reducing pain associated with dysmenorrhea. Details: Clinical research shows that taking calcium carbonate 1000 mg with vitamin D 5000 IU daily for three menstrual cycles does not reduce pain when compared with placebo in patients with primary dysmenorrhea (95821). However, calcium carbonate 1000 mg taken alone seems to reduce pain when compared with placebo.
• Endometrial cancer. It is unclear if oral calcium is beneficial for endometrial cancer prevention. Details: A meta-analysis of population research suggests that calcium supplements may reduce the risk of endometrial cancer, but dietary calcium does not seem to have any effect (38893).
• Fall prevention. It is unclear if oral calcium with vitamin D is beneficial for preventing falls. Details: Research suggests that calcium in combination with vitamin D, but not calcium alone, might prevent falls by decreasing body sway and normalizing systolic blood pressure (6362,11939,39038). Some experts think the combination of calcium and vitamin D may be important (11916). Preliminary clinical research in adults residing in a health care facility shows that taking vitamin D supplements while increasing dietary calcium and protein for 2 years reduces falls by 11% when compared with standard diets. Intervention diets were supplemented with milk, yogurt, and cheese to provide calcium 1142 mg and protein 69 grams daily (107235). There might also be different effects in females compared to males. In one study, females aged 65 years or older who took vitamin D 700 IU plus calcium citrate 500 mg daily over a 3-year period had a 46% lower risk of falling. However, this combination did not decrease falls in males (14291).
• Fluorosis. Oral calcium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Taking calcium orally, in combination with ascorbic acid (vitamin C) and vitamin D, seems to be effective for reducing excessive fluoride levels in children and improving symptoms of fluorosis in children aged 6-12 years (990).
• Heart failure. It is unclear if oral calcium in combination with vitamin D is beneficial for preventing heart failure. Details: Based on a secondary analysis of a large-scale clinical trial (Women's Health Initiative), taking calcium 1000 mg with vitamin D 400 IU daily does not reduce the risk of heart failure in the overall population or in individuals at high risk. However, in a subgroup of postmenopausal females without risk factors for heart failure, calcium and vitamin D supplementation might reduce the risk of developing heart failure by about 37% (97307).
• Hypercholesterolemia. It is unclear if oral calcium is beneficial for hypercholesterolemia. Details: Some evidence shows that taking calcium carbonate 400 mg three times daily reduces low-density lipoprotein (LDL) cholesterol levels by 4% and increases high-density lipoprotein (HDL) cholesterol levels by 4% after 6 weeks of treatment when used in combination with a low-fat diet (American Heart Association Step 1) (2557). In contrast, a study in females with dyslipidemia shows that taking calcium 800 mg daily for 2 years might INCREASE total cholesterol levels by about 12 mg/dL when compared with placebo. This same study showed an association between calcium supplementation and an increase in total cholesterol levels and carotid intimal thickness in postmenopausal females, but not premenopausal females (97350). A recent meta-analysis of randomized controlled trials which included both healthy patients and patients with dyslipidemia shows that taking calcium 500-2000 mg daily and vitamin D 200-7142 IU daily modestly improves HDL cholesterol and triglyceride levels, but not LDL cholesterol levels, when compared with placebo. Subgroup analyses suggest that calcium and vitamin D supplementation is more effective in patients with dyslipidemia at baseline. It is unclear if this effect is due to calcium, vitamin D, or the combination (107227). However, other research shows that taking a specific supplement containing calcium 600 mg plus vitamin D 200 IU (Caltrate 600 D, Wyeth Consumer Healthcare Inc.) twice daily in combination with calorie restriction does not reduce total or LDL cholesterol levels when compared with placebo (15601).
• Lead toxicity. It is unclear if oral calcium is beneficial for reducing blood levels of lead. Details: Lead is mobilized along with calcium from bone during pregnancy and lactation, resulting in increased serum concentrations of lead. One clinical study suggests that calcium supplementation does not significantly decrease these elevated lead concentrations (1586). However, another clinical study suggests that taking calcium reduces blood lead levels by 11% when compared with placebo, with greatest effects observed in those with high baseline levels of lead (38957).
• Lyme disease. Although there is interest in using oral calcium for Lyme disease, there is insufficient reliable information about the clinical effects of calcium for this condition.
• Metabolic syndrome. It is unclear if oral calcium alone or with vitamin D is beneficial for metabolic syndrome prevention. Details: Population research has found that a higher intake of calcium from diet and supplements alone, or in combination with vitamin D, is associated with a lower risk of developing metabolic syndrome when compared with lower calcium intake (14265,16713).
• Nephrotic syndrome. It is unclear if oral calcium with vitamin D is beneficial for preventing nephrotic syndrome. Details: Clinical research shows that taking calcium 500-1000 mg daily for 3 months in combination with vitamin D3 60,000 IU daily or weekly for 4 weeks has no effect on bone mineral density or the risk of relapse in children with steroid-sensitive nephrotic syndrome (97355).
• Nonmelanoma skin cancer. It is unclear if oral calcium is beneficial for preventing keratinocyte carcinomas. Details: In middle aged and older adults recently diagnosed with a colorectal adenoma, clinical research shows that taking calcium 1200 mg daily as calcium carbonate for 3-5 years does not reduce the incidence of keratinocyte cancer when compared with placebo over a median of 8 years. A sub-group analysis shows that taking calcium alone or with vitamin D3 1000 IU daily reduced the risk of invasive cutaneous squamous cell carcinoma by a moderate amount, but had no effect on the risk of basal cell carcinoma (104622).
• Oral mucositis. When used in combination with fluoride treatments, a calcium phosphate mouth rinse seems to prevent and reduce mucositis-related pain in patients undergoing hematopoietic stem cell transplantation (HSCT). Details: A small clinical study in patients undergoing HSCT shows that using a particular mouth rinse (Caphosol, EUSA Pharma) containing calcium phosphate, in combination with fluoride treatments, reduces days of mucositis, the duration of pain, and the dose and days of morphine used when compared with placebo and fluoride treatment (38611).
• Ovarian cancer. It is unclear if oral calcium is beneficial for ovarian cancer prevention. Details: An older meta-analysis of 12 cohort studies found that dietary calcium intake is not associated with a reduced risk of ovarian cancer (38792). However, a more recent pooled analysis of 15 cohort and case-control studies has found that the highest intake of dietary or dairy calcium is associated with a 20% lower risk of ovarian cancer when compared to the lowest intake (97349).
• Postpartum depression. It is unclear if oral calcium is beneficial for reducing postpartum depression risk. Details: Preliminary clinical research shows that taking calcium 2 grams daily beginning at 11-21 weeks gestation reduces depression at 12 weeks postpartum when compared with placebo. However, no benefit is seen at 6 weeks postpartum (39447).
• Pregnancy-related leg cramps. It is unclear if oral calcium is beneficial for preventing leg cramps during pregnancy. Details: A small clinical study shows that taking calcium 1 gram twice daily (as a mixture of salts) for 2 weeks can reduce pregnancy-related leg cramps during the second half of pregnancy when compared with no treatment (2567).
• Prostate cancer. It is unclear if oral calcium is beneficial for prostate cancer prevention. Details: Some clinical research shows that taking calcium 1200 mg daily might decrease the risk of developing prostate cancer (14133). However, some epidemiological research suggests that consuming very high doses of calcium, over 2000 mg daily, might actually increase the risk of developing prostate cancer (14134). Some epidemiological research also suggests that doses greater than 1500 mg daily increase the risk of poorly differentiated, clinically advanced, and fatal prostate cancer (14132). Consumption of dairy products has also been weakly linked to a modest increase in risk of prostate cancer (98894). However, contradictory research suggests that there is no association between dietary intake of calcium and overall risk of prostate cancer (14131,14132,104630).
• Stroke. It is unclear if oral calcium is beneficial for stroke prevention. Details: Some population research has found that increasing dietary calcium intake is associated with a decreased risk of ischemic stroke (4822,38678). However, other population research has found that increasing dietary calcium intake is not associated with a decreased risk of stroke (91350). One meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years does not affect the risk of stroke when compared with control. However, the majority of the included research evaluated postmenopausal females, and it is unclear if this finding is applicable to other populations (107233).
• Vertigo. Oral calcium with vitamin D might reduce positional vertigo; the effect of calcium when used alone is unclear. Details: A large clinical study in adults with recurrent benign paroxysmal positional vertigo shows that taking calcium 500 mg and vitamin D 400 IU twice daily for one year reduces annual recurrence of vertigo by 27% when compared with no treatment. The number needed to treat to prevent vertigo was 3.7 (103681). It is unclear if this benefit is due to vitamin D, calcium, or the combination. More evidence is needed to rate calcium for these uses.

(Read more about CALCIUM)

POSSIBLY EFFECTIVE

• Cataracts. Chondroitin sulfate in combination with sodium hyaluronate is approved as a medical device to be ophthalmically injected during cataract surgery. It is unknown if other routes of administration are beneficial. Details: Injecting ophthalmic viscosurgical devices (OVDs) containing a combination of chondroitin sulfate and sodium hyaluronate into the eye protects the corneal endothelium during small-incision cataract surgery. Various medical devices containing chondroitin sulfate and sodium hyaluronate (Viscoat, Alcon Laboratories) have been granted approval by US Food and Drug Administration (FDA) for use as an adjunct to cataract surgery (89436,89437). However, OVDs that cannot be easily removed after surgery can cause intraocular pressure (IOP) spikes and reduced visual acuity. A meta-analysis of small clinical studies shows that using a specific chondroitin sulfate 4% and sodium hyaluronate 3% solution (Viscoat, Alcon Laboratories) after small-incision cataract surgery increases IOP at postoperative days 1 and 2, but not at any later postoperative days for up to 1 month (104452).
• Osteoarthritis. Chondroitin sulfate seems to modestly reduce osteoarthritis pain and improve function. Pharmaceutical-grade chondroitin sulfate products have shown the most benefit. Details: Meta-analyses of randomized controlled trials in patients with mostly knee osteoarthritis show that taking chondroitin sulfate 800-2000 mg in single or divided doses daily for at least 3 months modestly reduces pain and disability when compared with placebo. However, included studies were heterogeneous and most had high attrition bias. A sub-group analysis of high-quality studies shows that 16 patients need to take chondroitin sulfate for 6 months for one patient to experience at least a 20% reduction in pain (94381,95792,99685,104446). When compared with conventional treatments like diclofenac 50 mg three times daily, chondroitin sulfate improves symptoms more slowly; however, the improvement seems to persist for up to 3 months after treatment cessation (322). Chondroitin also seems to have disease-modifying benefits. Clinical research in patients with osteoarthritis of the knee or hip shows that taking chondroitin sulfate 800 mg daily or more for 2 years might modestly reduce joint degeneration and narrowing when compared with placebo or celecoxib (42348,42398,94381,95516). Overall, most of the positive research involved pharmaceutical-grade chondroitin sulfate products, which are available as prescription products in some countries, such as Chondrosulf (IBSA Institut Biochimique SA) (17732,42348,42398,42536,89596,94360,104446), Chondrosan (Bioibérica, S.A.) (42463,42513), and Structum (Laboratoires Pierre Fabre) (22212,42520,89593). One clinical study shows that taking a pharmaceutical-grade chondroitin product (Chondrosulf) 800 mg daily seems to be comparable to taking celecoxib 200 mg daily for reducing pain and improving knee function (94360). Pharmaceutical-grade chondroitin products might demonstrate greater benefit due to higher quality (94360,102116). It is also important to note that most clinical studies using pharmaceutical-grade products are manufacturer-funded (94381). Furthermore, they may not be readily available for purchase in the US. Experts have conflicting stances on the use of chondroitin for osteoarthritis. The American College of Rheumatology (ACR) strongly recommends against the use of chondroitin for any form of osteoarthritis (102114). Conversely, the European Society of Clinical and Economic Aspects of Osteoarthritis (ESCEO) strongly recommends for the use of pharmaceutical-grade chondroitin products. Additionally, the ESCEO provides a weak recommendation against the use of chondroitin in combination with glucosamine (102141). These differing recommendations seem to be related to interpretation of the evidence for pharmaceutical-grade products. The ACR has determined that the inconsistent evidence may indicate the presence of industry bias; the ESCEO has determined that the inconsistent evidence is due to inconsistent product quality. Chondroitin is often used in combination with glucosamine and/or other products. Long-term studies in patients with osteoarthritis show that taking non-branded chondroitin sulfate with glucosamine sulfate modestly reduces joint-space narrowing when compared with control (89558,94380,95792). However, meta-analyses and individual clinical studies assessing non-branded preparations of chondroitin sulfate with glucosamine hydrochloride or glucosamine sulfate do not show reduced pain in patients with knee osteoarthritis when compared with control (13579,89558,95788,99683,99685). In contrast, pain reduction was reported for branded formulations such as chondroitin sulfate with glucosamine hydrochloride and manganese ascorbate (Cosamin DS, Nutramax Laboratories) (4237,7169); chondroitin sulfate with glucosamine hydrochloride (Droglican, Bioiberica, S.A.) (89516); or chondroitin sulfate with collagen peptides and hyaluronic acid (BioCell Collagen, BioCell Technology, LLC) (28678,28680). A large, prospective observational study in adults with knee or hip osteoarthritis suggests that taking glucosamine hydrochloride 500 mg and chondroitin sulfate 400 mg (Theraflex, Bayer) three times daily for the first 3 weeks, then twice daily thereafter for up to 64 weeks, is associated with reductions in pain, stiffness, and the need for concomitant analgesic therapy, and improvements in daily function and knee- or hip-related quality of life, when compared to baseline. The most pronounced improvements are from 16-24 weeks (111647). It is unclear if the benefit seen with these specific products is due to bias introduced by industry funding or due to higher quality. Limited research has also evaluated INTRAMUSCULAR and TOPICAL chondroitin. Some clinical research shows that receiving daily intramuscular injections of chondroitin sulfate for 6 months improves pain and function in patients with osteoarthritis (42396,42397). A topical preparation of chondroitin sulfate in combination with glucosamine sulfate, shark cartilage, and camphor also seems to reduce arthritis symptoms. However, any symptom relief is most likely due to the counterirritant effect of camphor and not the other ingredients (10327). There is no research showing that chondroitin is absorbed topically.

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Aging skin. Oral chondroitin sulfate has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in females with aging skin shows that taking a specific combination product (BioCell Collagen, BioCell Technology, LLC) containing chondroitin sulfate 200 mg, collagen peptides 600 mg, and hyaluronic acid 100 mg daily for 12 weeks reduces lines and wrinkles by about 13% when compared with baseline (28681). The validity of these findings is limited by the lack of a comparator group. It is also unclear if these improvements are due to chondroitin sulfate, other ingredients, or the combination. Furthermore, it should be noted that this study was funded by the product manufacturer.
• Aromatase inhibitor-induced arthralgia. Oral chondroitin sulfate has only been evaluated in combination with glucosamine sulfate; its effect when used alone is unclear. Details: A small open-label clinical study in postmenopausal females with early stage breast cancer shows that taking a combination of glucosamine sulfate 1500 mg and chondroitin sulfate 1200 mg in 2-3 divided doses daily for 24 weeks improves pain and symptoms associated with aromatase inhibitor-induced arthralgias when compared to baseline (89561). The validity of this finding is limited by the lack of a control group.
• Cancer. Some low-quality observational studies suggest that oral chondroitin use is not associated with a lower risk of cancer. Details: A meta-analysis of observational research has found that use of chondroitin with or without glucosamine is not associated with a lower risk of cancer when compared with no use (110625).
• Colorectal adenoma. Oral chondroitin has only been evaluated in combination with glucosamine; its effect when used alone is unclear. Details: An observational study in older adults has found that taking oral chondroitin and glucosamine is associated with a 26% reduced chance of high-risk adenoma and 10% reduced chance of conventional adenoma when compared with not using these supplements. This benefit was not seen in a subgroup of younger females (104444).
• Dry eye. It is unclear if ophthalmic chondroitin sulfate improves dry eye symptoms. Details: A small clinical study in patients with dry eye suggests that administering an ophthalmic preparation of chondroitin sulfate every two hours while awake for 2 weeks seems to improve symptoms when compared to baseline (1974). Chondroitin has also been used in combination with other ingredients. A large clinical trial in patients with mild to moderate dry eye disease shows that applying preservative-free eye drops containing chondroitin sulfate with sodium hyaluronate (Humylub Ofteno PF, Laboratorios Sophia), one drop into each eye four times daily for 90 days, seems to be no different for improving dry eye severity when compared with using polyethylene/propylene glycol eye drops (Systane Ultra, Alcon Laboratories) (104443). Another small clinical trial in patients with mild to moderate dry eye shows that using specific eye drops containing chondroitin sulfate and xanthan gum (PRO-148, Laboratorios Sophia) four times daily for 60 days does not improve tear stability, but might improve dry eye severity, when compared with using polyethylene/propylene glycol eye drops (Systane, Alcon Laboratories) (89591).
• Exercise-induced muscle soreness. It is unclear if oral chondroitin sulfate improves muscle soreness from exercise. Details: Preliminary clinical research in untrained males shows that taking chondroitin sulfate 1800 mg twice daily for 14 days before exercise does not reduce post-exercise muscle soreness when compared with placebo (42352). However, another small clinical study in healthy, recreationally active adults shows that a specific combination product (BioCell Collagen, BioCell Technology, LLC) containing chondroitin sulfate 300 mg, collagen peptides 900 mg, and hyaluronic acid 150 mg, taken twice daily for 6 weeks prior to two bouts of resistance exercise, attenuates muscle damage and decreases delayed-onset muscle soreness when compared with placebo (96301). It is unclear if these effects are due to chondroitin sulfate, the other ingredients, or the combination.
• Gastroesophageal reflux disease (GERD). Oral chondroitin sulfate has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Patients with non-erosive GERD are thought to be less responsive to conventional acid suppression with proton pump inhibiters (PPIs) and H-2 blockers. A small preliminary clinical study shows that taking a syrup containing hyaluronic acid and chondroitin sulfate along with PPIs, H2-receptor antagonists, and/or antacids, reduces the intensity of symptoms associated with non-erosive GERD by about 3.5-fold when compared with placebo (89592). A larger clinical study in patients with non-erosive GERD shows that taking the same combination agent (Esoxx by Alfa Wassermann) in addition to acid suppression with PPIs improves GERD symptom severity by 21%, heartburn by 15%, and regurgitation by 10% when compared with PPIs with a placebo (101271). This product is available in Canada as EsopH (Exzell Pharma). It is unclear if the benefit of this combination product is due to chondroitin sulfate, hyaluronic acid, or the combination. Chondroitin sulfate has also been evaluated in patients with GERD who experience extraesophageal symptoms. A small clinical study in patients reporting symptoms of cough, hoarseness, postnasal drip, sore throat, and/or throat clearing shows that taking a specific combination product (Gerdoff, SOFAR S.p.A.) containing chondroitin sulfate, hyaluronic acid, and aluminum hydroxide three times daily with omeprazole 40 mg once daily for 6 weeks does not reduce overall symptom scores, based on the Reflux Symptoms Index (RSI) score, when compared with omeprazole alone. However, it does increase the probability of treatment response, defined as a 50% or greater improvement in RSI score, by nearly 40% (109648). This product is available in Italy. It is unclear if these findings are due to chondroitin sulfate, other ingredients, or the combination.
• Gastritis. Oral chondroitin sulfate has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with gastritis shows that taking a specific liquid product (Esoxx, Alfa Wasserman Spa) containing chondroitin sulfate and hyaluronic acid four times daily for 4 weeks modestly reduces upper abdominal pain when compared with placebo (99687). It is not clear if this effect is due to chondroitin sulfate, hyaluronic acid, or the combination.
• Hyperlipidemia. Although there is interest in using oral chondroitin for hyperlipidemia, there is insufficient reliable information about the clinical effects of chondroitin for this condition.
• Interstitial cystitis. Small clinical studies suggest that intravesical chondroitin sulfate may not improve interstitial cystitis symptoms. Oral chondroitin sulfate has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Several uncontrolled, open-label studies suggest that intravesical chondroitin sulfate, with or without hyaluronic acid, improves clinical symptoms of interstitial cystitis and reduces the problems caused by symptoms in these patients (42338,42371,42373,42385,42387). However, in controlled clinical trials, intravesical chondroitin sulfate 2%, instilled weekly for 6-7 weeks, does not significantly improve symptoms when compared with a placebo solution (42473,42517). Furthermore, a meta-analysis of clinical research shows that intravesical chondroitin sulfate with hyaluronic acid does not improve pain due to interstitial cystitis better than using hyaluronic acid solution alone (97054). Oral chondroitin has been evaluated in combination with other ingredients. Preliminary clinical research shows that taking a specific product (CystoProtek, Tischon Corporation) containing glucosamine sulfate 120 mg, sodium hyaluronate 10 mg, chondroitin sulfate 150 mg, quercetin 150 mg, and rutin 20 mg, as two capsules twice daily for 12 months, reduces symptoms of interstitial cystitis by 44% to 52% (42391). It is not clear if this effect is due to chondroitin, other ingredients, or the combination.
• Kashin-Beck disease. It is unclear if oral chondroitin sulfate improves Kashin-Beck disease symptoms such as pain. Details: A small clinical study in Chinese adults with Kashin-Beck disease shows that taking chondroitin sulfate 600 mg twice daily with or without glucosamine hydrochloride 480 mg three times daily for 6 months decreases pain and stiffness when compared with placebo (42516).
• Osteoporosis. Although there is interest in using oral chondroitin for osteoporosis, there is insufficient reliable information about the clinical effects of chondroitin for this condition.
• Overall mortality. Oral chondroitin has only been evaluated in combination with glucosamine; its effect when used alone is unclear. Details: A cross-sectional observational study suggests that using oral chondroitin and glucosamine for at least one year is associated with a 27% lower incidence of overall mortality and 58% lower incidence of cardiovascular mortality when compared with not using these supplements (104445). However, this study did not clarify the forms of chondroitin and glucosamine used, or the doses, frequencies, or durations of use. Furthermore, the adults that reported glucosamine and chondroitin use also reported overall healthier lifestyle habits than those that were not taking glucosamine and chondroitin. Another observational study suggests that regular use of chondroitin with glucosamine for an average of 8 years is associated with a 30% lower risk of mortality when compared with no use. However, when these findings are adjusted for differences in age, body mass index, and comorbidities, overall mortality risk does not seem to be reduced with chondroitin and glucosamine supplementation (110626). Higher quality, prospective research is needed to clarify the relationship, if any, with overall mortality. Additionally, it is unclear if the effects on mortality are due to chondroitin, glucosamine, or the combination.
• Psoriasis. It is unclear if oral chondroitin sulfate is beneficial for reducing psoriasis disease severity. Details: A clinical study in patients with plaque psoriasis and knee osteoarthritis shows that taking chondroitin sulfate (Condrosan, CS Bio-Active, Bioibérica S.A.) 800 mg daily for 3 months does not appear to reduce the extent or severity of plaque psoriasis when compared with placebo (42463).
• Stroke. It is unclear if oral chondroitin sulfate is beneficial for reducing stroke risk. Details: An observational study in Spanish patients found that chondroitin sulfate use is associated with 23% lower odds of ischemic stroke when compared with non-use; however, the benefit was only observed in patients taking at least 800 mg for no more than one year (109643).
• Temporomandibular disorders (TMD). Oral and topical chondroitin sulfate has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A meta-analysis of two small clinical studies in patients with TMD shows that taking chondroitin sulfate 1200 mg and glucosamine sulfate 1500 mg daily for 2 months does not reduce pain or increase maximum mouth opening when compared with tramadol 50-100 mg daily (109647). Another small clinical trial in children aged 10-13 years with class II malocclusion shows that application of a specific combination gel product containing glucosamine, chondroitin, and essential oils (Jointace Gel, Vitabiotics) with an expander device twice daily for 3 months does not improve pain, tension, or temporomandibular space measures when compared with placebo (110629).
• Urinary incontinence. Although there is interest in using intravesical chondroitin for urinary incontinence, there is insufficient reliable information about the clinical effects of chondroitin for this condition.
• Urinary tract infections (UTIs). It is unclear if intravesical administration of chondroitin sulfate alone is beneficial in patients with recurrent UTIs. Most research has evaluated the effects of chondroitin sulfate in combination with hyaluronic acid, with promising results. Details: One small observational study in patients with recurrent UTIs has found that intravesical administration of 40 mL of chondroitin sulfate 0.2% weekly for 6 weeks, then every 2 weeks for 2 months, then every 3 weeks for 2 months, and finally every 6 weeks for a total treatment duration of 1 year is associated with a lower number of UTIs and urologist visits when compared with low-dose long-term antibiotic therapy (109649). Most research on the use of chondroitin sulfate for UTIs has evaluated its effects when used in combination with hyaluronic acid. Several small clinical studies and a pooled analysis of the available clinical research show that intravesical administration of 50 mL of specific solutions containing chondroitin sulfate 2% and hyaluronic acid 1.6% (iAluRil, IBSA Farmaceutici; Cystistat, Bioniche) for up to 6 months reduces the rate of UTI recurrence by about 2-3 incidents per year and delays the time to the first UTI recurrence when compared with placebo or prophylaxis with sulfamethoxazole-trimethoprim (42511,42519,89590,89594,99688). However, the validity of these findings is limited by the low quality and high heterogeneity of the included studies, as well as concerns for publication bias (99688). More evidence is needed to rate chondroitin sulfate for these uses.

(Read more about CHONDROITIN SULFATE)

LIKELY EFFECTIVE

• Osteoarthritis. Oral glucosamine sulfate taken for at least 4 weeks is modestly beneficial for improving pain and function in knee osteoarthritis. However, oral glucosamine hydrochloride seems to only be beneficial when used in combination with chondroitin and other ingredients. It is unclear if glucosamine can slow disease progression or improve symptoms in other forms of osteoarthritis. Details: Meta-analyses of the available research in adults with KNEE osteoarthritis show that taking glucosamine SULFATE 1500 mg daily for up to 3 years modestly improves pain, function, and joint space narrowing when compared with placebo (14305,89521,94382,95785,99684,113636). Individual studies show 28% to 41% pain reduction and 21% to 46% improvement in function when compared with placebo (7026,8942,12461,20084,94382). Some research suggests that glucosamine sulfate reduces pain similarly to various non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen 400 mg three times daily and piroxicam 20 mg daily. However, NSAIDs appear to relieve symptoms within 2 weeks, while glucosamine sulfate takes 4-8 weeks. Notably, glucosamine sulfate appears to sustain benefit for longer after treatment withdrawal when compared with piroxicam (2604,20094,20096). Other clinical research shows that glucosamine sulfate 1500 mg once daily for 6 months might be more effective for reducing symptoms than acetaminophen 1 gram three times daily or 650 mg once daily in patients with moderate knee osteoarthritis (13578,20098). However, not all research shows benefit. One meta-analysis of clinical studies in adults with knee osteoarthritis shows that taking glucosamine sulfate 1500 mg daily for 4 weeks to 3 years reduces some, but not all, measures of pain intensity and does not reduce pain when moving or improve function when compared with placebo (113636). Furthermore, small clinical studies suggest that glucosamine sulfate 1500 mg daily for 2-6 months may NOT work for severe, long-standing osteoarthritis (1330,11459). It is unclear if glucosamine sulfate can slow disease progression. A specific crystalline glucosamine sulfate product (Dona, Rotta Pharmaceuticals) taken as 1500 mg daily for up to 3 years seems to prevent joint space narrowing of greater than 0.5 mm by up to 54% when compared with placebo (7026,8942,13719,42420). In contrast, other glucosamine sulfate formulations have not consistently been shown to improve symptoms or prevent joint space narrowing when compared with placebo (14305,89558,94382,95788). It is unclear if the benefit seen with this specific product (Dona) is due to bias introduced by industry funding or due to a higher quality product (42492). Glucosamine products associated with quality concerns have demonstrated inconsistent benefits in research (8128,102116). Limited research on the use of a different salt, glucosamine HYDROCHLORIDE, has found no benefit for knee osteoarthritis. A meta-analysis of clinical research and two other clinical trials show that taking glucosamine hydrochloride 1500 mg daily for up to 18 months does not seem to reduce pain when compared with placebo (18344,89519,89521). However, one small, unblinded clinical study in patients with mild to moderate osteoarthritis shows that taking a combination of glucosamine hydrochloride 480 mg every 12 hours and celecoxib 200 mg daily reduces pain scores, osteoarthritis severity, and inflammatory markers to a greater extent than celecoxib alone (106883). There is mixed evidence of benefit when glucosamine hydrochloride is used with chondroitin. Clinical research in patients over 40 years of age shows that taking a noncommercial preparation of glucosamine hydrochloride 1500 mg daily in combination with chondroitin sulfate 1200 mg daily for 6-24 months does not reduce pain when compared with placebo. The placebo response in these studies was sometimes as high as 60% (13579,14809,42477). However, a large, prospective observational study in adults with knee or hip osteoarthritis suggests that taking glucosamine hydrochloride 500 mg and chondroitin sulfate 400 mg (Theraflex, Bayer) three times daily for the first 3 weeks then twice daily thereafter for up to 64 weeks is associated with reductions in pain, stiffness, and the need for concomitant analgesic therapy and improvements in daily function and knee- or hip-related quality of life when compared to baseline. The most pronounced improvements were from 16-24 weeks (111647). The validity of these effects is limited by subjective outcomes, a lack of control group, and the observational design of the study. Furthermore, another clinical trial shows that taking a prescription product available in Spain (Droglican, Bioibérica S.A.), providing a similar daily dose of glucosamine hydrochloride with chondroitin sulfate for 6 months is non-inferior to celecoxib 200 mg daily for relieving pain, but not stiffness or function (89516). Small clinical studies show that taking a specific combination product (Cosamin or Cosamin DS, Nutramax Laboratories) containing glucosamine hydrochloride 1500-2000 mg, low molecular weight chondroitin sulfate 1200-1600 mg, and manganese ascorbate 228-304 mg, in 2-3 divided doses daily for 2-6 months improves pain in patients with mild or moderate, but not severe, osteoarthritis when compared with placebo (4237,7169). A different combination product (Gurukosamin & Kondoroichin, Suntory Wellness Ltd.) containing glucosamine hydrochloride 1200 mg, chondroitin sulfate 60 mg, and quercetin glycosides 45 mg, taken daily for 16 weeks, also seems to improve symptoms of knee osteoarthritis when compared with placebo (42514). It is unclear if the findings of any of these studies are due to glucosamine, chondroitin, other ingredients, or the combination. Despite evidence suggesting differing benefit (89521,94382), head-to-head comparisons of glucosamine sulfate and glucosamine hydrochloride are limited, and it is not universally acknowledged that these salts have different effectiveness profiles. One large clinical study in patients with knee osteoarthritis shows that taking a specific product (Artrolive, Aché Laboratórios Farmacêuticos S.A.) containing glucosamine sulfate 500 mg and chondroitin sulfate 400 mg three times daily for 4 months seems to be no different for reducing pain when compared with taking glucosamine hydrochloride 500 mg and chondroitin sulfate 400 mg (Cosamin DS, Nutramax Laboratories, Inc.) three times daily (89520). This study was funded by the supplement manufacturer. Many meta-analyses have pooled studies of both glucosamine salts together, producing largely inconsistent results (94381,99683,99685,112444). Experts have conflicting stances on the use of glucosamine. The American College of Rheumatology (ACR) strongly recommends against the use of any glucosamine products for any form of osteoarthritis (102114). Conversely, the European Society of Clinical and Economic Aspects of Osteoarthritis (ESCEO) strongly recommends the use of pharmaceutical-grade glucosamine sulfate products, such as Dona (Rotta Pharmaceuticals), in patients with osteoarthritis. Additionally, the ESCEO provides a weak recommendation against the use of glucosamine in combination with chondroitin (102141). These differing recommendations seem to be related to interpretation of the evidence for pharmaceutical-grade products. The ACR has determined that the inconsistent evidence may indicate the presence of industry bias; the ESCEO has determined that the inconsistent evidence is due to inconsistent product quality. Limited research has found mixed benefit of using glucosamine on osteoarthritis of the SPINE, HIP, or HAND. In one study of patients with osteoarthritis of the lumbar spine, taking glucosamine sulfate (Dona, Rotta Pharmaceuticals) 1500 mg daily for 6 weeks reduced pain in more patients when compared with placebo (1316). However, in another study, using a different glucosamine sulfate product (Glucosamine Sulfate, PharmaNord) 1500 mg daily for 6 months did not reduce pain when compared with placebo (89562). In patients with hip osteoarthritis, taking glucosamine sulfate 1500 mg once daily for 2 years did not reduce symptoms or slow disease progression when compared with placebo (16717,20100); however, there was a high rate of hip replacement, which may have confounded results (16717,16718). In patients with erosive osteoarthritis of the hand, observational research has found that taking glucosamine sulfate (Dona, Rotta Pharmaceuticals) 1500 mg daily along with conventional therapy for 6 months is associated with reduced hand pain, a shorter duration of morning stiffness, and improved hand function when compared with conventional therapy alone (108897). Limited research has also evaluated INTRAMUSCULAR and TOPICAL glucosamine sulfate. A clinical study in patients with mild to moderate knee osteoarthritis (radiological stage I-III) shows that giving intramuscular glucosamine sulfate 400 mg twice per week for 6 weeks reduces the severity of symptoms when compared with placebo (2605). There is also a small study showing that a topical preparation of glucosamine sulfate in combination with chondroitin sulfate, shark cartilage, and camphor reduces osteoarthritis symptoms when compared with placebo. However, any symptom relief is most likely due to the counterirritant effect of camphor and not the other ingredients (10327,12467). There is no evidence that glucosamine is absorbed topically. Glucosamine sulfate does not seem to PREVENT osteoarthritis. Clinical studies in overweight healthy females aged 50-60 years shows that taking crystalline glucosamine sulfate 1500 mg orally daily for 2.5 years does not reduce the incidence of osteoarthritis after a 6-7 year follow-up; however, it may reduce the percentage of patients who experience knee joint space narrowing (95789,97053).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Aging skin. Topical N-acetyl glucosamine has only been evaluated in combination with niacinamide for reducing hyperpigmentation and liver skin spots on aging skin; its effect when used alone is unclear. Details: A clinical study in females ages 40-60 years with skin hyperpigmentation and solar lentigines (liver spots) primarily due to aging and sun exposure shows that applying a cream containing 2% N-acetyl glucosamine and 4% niacinamide to the face twice daily with sunscreen for 10 weeks decreases facial hyperpigmentation when compared with sunscreen alone (92721). The effect of N-acetyl glucosamine alone is unclear.
• Aromatase inhibitor-induced arthralgia. Oral glucosamine sulfate has only been evaluated in combination with chondroitin; its effect when used alone is unclear. Details: A small open-label clinical study in patients with aromatase inhibitor-induced arthralgia shows that taking a combination of glucosamine sulfate 1500 mg and chondroitin sulfate 1200 mg in 2-3 divided doses daily for 24 weeks improves pain when compared to baseline in postmenopausal adults with early stage breast cancer (89561). The validity of this finding is limited by a lack of control group.
• Back pain. Although there is interest in using oral glucosamine for back pain, there is insufficient reliable information about the clinical effects of glucosamine for this condition.
• Cancer. Some low-quality observational studies have inconsistently found that glucosamine may be associated with a lower risk of different cancers; however, better quality evidence is needed. Details: A meta-analysis of observational research has found that use of glucosamine with or without chondroitin is associated with a 7% to 12% lower risk of cancer when compared with no use of glucosamine. A subgroup analysis showed a reduction in the risk of colorectal cancer, but not other types of cancer (110625). Observational research report conflicting relationships between glucosamine and cancer. Some observational research in adults in the United Kingdom has found that taking glucosamine is associated with 4% higher risk of cancer over a median follow up for 13 years. However, a subgroup analysis showed a reduction in the risk of lung cancer (110627). Other observational research in adults in the United Kingdom has found that taking glucosamine is associated with a 5% reduced risk of cancer mortality over a median follow-up of around 12 years, with reductions specifically occurring in those with kidney, lung, and rectal cancers. However, glucosamine use was not linked to a reduced risk of mortality due to bladder, brain, breast, colon, ovarian, prostate, skin, stomach, thyroid, or uterine cancer (109645). Other large, propensity-score-adjusted, observational research in adults with osteoarthritis in the United Kingdom suggests that treatment with glucosamine, with an average of 8 years of follow-up, is not associated with a reduction in cancer, including lung, colorectal, breast, or prostate cancer, when compared with patients not prescribed glucosamine (114571). These studies are limited by observational designs, which also did not clarify the form of glucosamine used, or the dose, frequency, or duration of use. Furthermore, the adults that reported glucosamine use also reported overall healthier lifestyle habits than those that were not taking glucosamine. Although some studies attempted to control for these differences, higher quality, prospective research is needed to clarify the relationship, if any, between glucosamine and the risk for cancer and/or cancer-related mortality. Of note, some researchers have called into question the results from observational research linking glucosamine use to a lower rate of cancer, claiming that these studies suffer from a high risk of selection bias (109646).
• Cardiovascular disease (CVD). It is unclear if oral glucosamine prevents fatal or non-fatal CVD events. Details: Some observational research of adults in the United Kingdom has found that taking glucosamine is associated with an overall 15% reduced risk for fatal and non-fatal CVD events, including coronary heart disease (CHD) and stroke (99682). However, this study did not clarify the form of glucosamine used, or the dose, frequency, or duration of use. Furthermore, the adults that reported glucosamine use also reported overall healthier lifestyle habits than those that were not taking glucosamine. Conversely, an observational study in Chinese patients with osteoarthritis has found that glucosamine use is associated with a 10% increase in the risk of CVD events and a 12% increase in the risk of CHD, with no increase in the risk of stroke. The risk for these outcomes was greatest in patients with higher adherence to glucosamine and in those taking larger doses (109642). However, this study also did not clarify the form of glucosamine used or provide specifics related to the frequency or duration of use. Furthermore, glucosamine users were generally older, more likely to be on antihyperlipidemic or antiplatelet therapy, and more likely to have multiple comorbidities compared with non-users. Both studies attempted to control for the differences in characteristics between glucosamine users and non-users; despite this, higher quality, prospective research is needed to clarify the relationship, if any, between glucosamine and CVD risk.
• Colorectal adenoma. Oral glucosamine has only been evaluated in combination with chondroitin; its effect when used alone is unclear. Details: An observational study in older adults has found that taking glucosamine and chondroitin is associated with a 26% reduced risk of high-risk adenoma and 10% reduced risk of conventional adenoma when compared with not using these supplements. This benefit was not seen in a subgroup of younger females (104444). This study did not clarify the form of glucosamine used, or the dose, frequency, or duration of use.
• Colorectal cancer. It is unclear if oral glucosamine reduces the risk of colorectal cancer. Details: A meta-analysis of observational research has found that use of glucosamine with or without chondroitin is associated with a 7% to 12% lower risk of cancer when compared with no use of glucosamine. A subgroup analysis showed a reduction in the risk of colorectal cancer, but not other types of cancer (110625). However, not all research agrees. A large, observational study in adults has found that regular use of oral glucosamine is not associated with a reduced risk of colorectal cancer over a median of 7 years of follow-up, regardless of sex, age, body mass index, smoking status, or non-steroidal anti-inflammatory drug use (108018). Other large, propensity-score-adjusted, observational research in adults with osteoarthritis in the United Kingdom suggests that treatment with glucosamine, with an average of 8 years of follow-up, is not associated with a reduction in cancer, including colorectal cancer, when compared with patients not prescribed glucosamine (114571).These studies did not clarify the form or dose of glucosamine used or the frequency or duration of use.
• Coronavirus disease 2019 (COVID-19). It is unclear if oral glucosamine is beneficial for COVID-19. Details: A large observational study in adults suggests that regular glucosamine use over a median of 1.7 years is not linked to a lower odds of COVID-19 infection but is associated with a 20% lower risk of hospital admission and a 19% lower risk of mortality due to COVID-19 when compared with adults not using glucosamine (111649). This study did not clarify the form or dose of glucosamine used or the frequency or duration of use.
• Dementia. Observational studies suggest that long-term, regular glucosamine intake might reduce the risk of developing certain types of dementia. Details: An observational study has found that regularly taking glucosamine for an average of 8.9 years is associated with a 19% lower risk of developing dementia, including Alzheimer disease and vascular dementia (110630). Another large observational study in older adults without dementia suggests that regularly taking glucosamine for a median of 12 years is associated with an 18% lower risk of vascular dementia. However, habitual glucosamine consumption is not associated with a reduced risk of Alzheimer disease or frontotemporal dementia (112461).
• Depression. It is unclear if oral glucosamine hydrochloride reduces depression symptoms. Details: A small, open-label clinical trial in patients with unipolar depression shows that taking glucosamine hydrochloride 1 gram daily for 1 week, followed by 2 grams daily for 3 weeks, reduces scores on the Hamilton Rating Scale for Depression (HAM-D) and Montgomery-Asberg Depression Rating Scale (MADRS) by 31% or 33% when compared to baseline. However, only 20% of patients experienced a 50% or greater reduction in HAM-D scores, and there were no improvements in Clinical Global Impression scores (103281). The lack of a control group limits the validity of these findings.
• Diabetes. It is unclear if oral glucosamine reduces the risk of developing type 2 diabetes in adults. Details: Observational research in adults in the United Kingdom has found that glucosamine use is associated with a 17% lower risk of type 2 diabetes. The relationship between glucosamine use and diabetes appears to be even more pronounced in patients with high baseline levels of C-reactive protein, a marker of inflammation (103234). However, this study did not clarify the form of glucosamine used, or the dose, frequency, or duration of use. Furthermore, the adults that reported glucosamine use also reported overall healthier lifestyle habits than those that were not taking glucosamine. Although this study attempted to control for these differences, higher quality, prospective research is needed to clarify the relationship, if any, between glucosamine and the risk for diabetes.
• Gout. It is unclear if oral glucosamine reduces the risk of developing gout. Details: Observational research in adults in the United Kingdom has found that glucosamine use is associated with a 19% lower risk of gout in females, but not males (109644). However, this study did not clarify the form of glucosamine used, or the dose, frequency, or duration of use. Furthermore, the adults that reported glucosamine use also reported overall healthier lifestyle habits than those that were not taking glucosamine. Although this study attempted to control for these differences, higher quality, prospective research is needed to clarify the relationship, if any, between glucosamine and the risk for gout.
• Heart failure. It is unclear if oral glucosamine prevents heart failure. Details: A large, prospective observational study in adults without heart failure suggests that taking glucosamine regularly over a median of 9 years is associated with a 13% lower risk of developing heart failure when compared with adults not taking glucosamine (111646). This study did not clarify the form or dose of glucosamine used or the frequency or duration of use.
• Hyperlipidemia. It is unclear if oral glucosamine hydrochloride improves hyperlipidemia when used with conventional medicine. Details: Preliminary clinical research shows that glucosamine hydrochloride does not reduce cholesterol or triglyceride levels in patients with hyperlipidemia. A small crossover study in older adults taking simvastatin or atorvastatin shows that adding a specific glucosamine hydrochloride product (Artrox, Pfizer) 750 mg twice daily for 4 weeks does not seem to affect lipid levels when compared with placebo (18341).
• Inflammatory bowel disease (IBD). It is unclear if oral or rectal N-acetyl glucosamine improves symptoms of IBD in children. Details: A very small clinical study in children ages 8-17 years with Crohn disease or ulcerative colitis that were unresponsive to conventional treatment suggests that oral or rectal N-acetyl glucosamine 1.5-2 grams in 10 mL water twice daily for 6 weeks might decrease symptoms of IBD when compared with baseline (10234). The validity of this finding is limited by a lack of control group.
• Interstitial cystitis. Oral glucosamine sulfate has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: An open-label clinical study in patients with interstitial cystitis shows that taking a specific product (CystoProtek, Tischon Corporation) containing glucosamine sulfate 120 mg, sodium hyaluronate 10 mg, chondroitin sulfate 150 mg, quercetin 150 mg, and rutin 20 mg per capsule, as two capsules twice daily for 12 months, reduces symptom severity by up to 52% when compared with baseline (42391). The validity of this finding is limited by a lack of control group.
• Joint pain. Oral glucosamine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with joint pain shows that taking capsules of a specific combination product (Instaflex Joint Support, Direct Digital) containing glucosamine sulfate 1500 mg, methylsulfonylmethane 500 mg, white willow bark extract 250 mg, ginger root concentrate 50 mg, Boswellia serrata extract 125 mg, turmeric root extract 50 mg, cayenne 40 m H.U. 50 mg, and hyaluronic acid 4 mg, daily in three divided doses for 8 weeks, reduces joint pain severity by 37% compared to only 16% with placebo. However, the specific combination product does not appear to improve joint stiffness or function compared with placebo (89560).
• Kashin-Beck Disease. It is unclear if oral glucosamine hydrochloride improves Kashin-Beck Disease symptoms such as pain. Details: A small clinical study in Chinese adults with Kashin-Beck Disease shows that taking glucosamine hydrochloride 480 mg three times daily along with chondroitin sulfate 600 mg twice daily for 6 months decreases pain scores by at least 20% to 50% in more patients when compared with placebo. Taking glucosamine alone had a non-significant trend toward pain reduction in these patients (42516). An open-label study in Chinese adults with Kashin-Beck Disease shows that taking glucosamine hydrochloride 750 mg twice daily for 6 weeks seems to be no different for improving pain and physical function when compared with taking to diclofenac 50 mg twice daily or naproxen 300 mg twice daily (18339). The validity of this finding is limited by a lack of blinding.
• Kidney stones (nephrolithiasis). Oral glucosamine might reduce the risk of developing kidney stones. Details: A large observational study in adults without kidney stones suggests that regularly taking glucosamine is associated with a 28% lower risk of new-onset kidney stones in people with a total sedentary time under 3.5 hours daily. This association follows a dose-dependent relationship. However, regular glucosamine use does not seem to reduce the risk of new-onset kidney stones in people with total sedentary time exceeding 3.5 hours daily (112451).
• Knee pain. Small clinical studies suggest that oral glucosamine hydrochloride might improve exercise-induced knee pain and chronic knee pain. However, it is unclear if glucosamine sulfate, N-acetyl glucosamine, or lower doses of glucosamine hydrochloride are beneficial in these patients. Details: A small clinical study in athletes following an acute knee injury shows that taking glucosamine sulfate 500 mg three times daily for 28 days does not improve pain but might modestly improve mobility when compared with placebo (20103). Glucosamine has also been evaluated for chronic knee pain. A small clinical study in patients with chronic knee pain of unclear origin shows that taking glucosamine hydrochloride 2000 mg daily for 12 weeks might modestly improve pain when compared with placebo (10312). However, lower doses of glucosamine hydrochloride and N-acetyl glucosamine used in combination with other ingredients have not demonstrated benefit for chronic knee pain. A small clinical trial in Japanese adults over 40 with knee pain shows that taking a combination supplement with glucosamine hydrochloride and other ingredients for 16 weeks does not improve pain, function, or walking speed when compared with placebo. The combination supplement provided glucosamine hydrochloride 1200 mg, chondroitin sulfate 60 mg, type II collagen peptides 45 mg, quercetin glycosides 90 mg, imidazole peptides 10 mg, and vitamin D 200 IU daily (95784). Another small clinical study in Japanese patients over 50 years of age with chronic knee pain shows that taking a specific supplement (Walker's Glucosamine, Kyowa) containing N-acetyl glucosamine 100 mg and chondroitin sulfate 180 mg daily for 24 weeks does not reduce pain or improve knee function when compared with placebo (95795).
• Metabolic dysfunction-associated steatotic liver disease (MASLD). It is unclear if oral glucosamine is beneficial in patients with MASLD. Details: Observational research in adults with MASLD and type 2 diabetes suggests that regular use of glucosamine orally for an average follow up of 11 years is associated with a lower risk of adverse liver outcomes when compared with those not regularly using glucosamine. Non-users of glucosamine had 35% to 44% higher risk of cirrhosis, encephalopathy, and esophageal varices. This study did not report the glucosamine dose or frequency (114573).
• Multiple sclerosis (MS). It is unclear if oral glucosamine sulfate is beneficial in patients with MS. Details: A small clinical study in patients with MS shows that taking glucosamine sulfate 1000 mg once daily for 6 months modestly reduces relapse when compared to baseline, but not when compared with placebo (20104).
• Overall mortality. It is unclear if oral glucosamine reduces overall mortality. Details: An observational study in the United States has found that regular use of oral glucosamine, with or without chondroitin, for an average of 8 years is associated with a 30% lower risk of mortality when compared with no glucosamine use. However, when adjusted for covariates such as age, body-mass index, and comorbidities, there was no difference in overall mortality (110626). In contrast, a cross-sectional observational study has found that using oral glucosamine and chondroitin for at least one year is associated with 27% reduced incidence of overall mortality and 58% reduced incidence of cardiovascular mortality when compared with not using these supplements (104445). This study did not clarify the form of glucosamine used, or the dose, frequency, or duration of use. Furthermore, the adults that reported glucosamine and chondroitin use also reported overall healthier lifestyle habits than those that were not taking glucosamine and chondroitin. Although this study attempted to control for these differences, higher quality, prospective research is needed to clarify the relationship, if any, with overall mortality. Of note, some researchers have called into question the results from observational research linking glucosamine use to a lower rate of overall mortality, claiming that these studies suffer from a high risk of selection bias (109646).
• Postoperative recovery. It is unclear if oral glucosamine sulfate improves recovery after surgery. Details: A small clinical study in male athletes who have undergone anterior cruciate ligament (ACL) reconstruction shows that taking glucosamine sulfate (Solgar Inc.) 1000 mg daily for 8 weeks does not improve rehabilitation outcomes such as functional ability, pain, and muscular performance when compared with placebo (95584).
• Rheumatoid arthritis (RA). It is unclear if oral glucosamine hydrochloride is beneficial in patients with RA. Details: A small clinical study in patients with RA shows that taking glucosamine hydrochloride tablets (Rohto Pharmaceutical Co.) 500 mg three times daily by mouth for 12 weeks reduces pain, but not the number of painful or swollen joints, when compared with placebo (17407).
• Stroke. It is unclear if oral glucosamine is beneficial for reducing stroke risk. Details: An observational cohort study of adults in the United Kingdom found that taking glucosamine is associated with a modest 9% reduced risk for overall stroke; however, sub-analyses show that glucosamine use is not associated with a reduced risk for fatal or non-fatal stroke, hemorrhagic stroke, or ischemic stroke (99682). This study did not clarify the form of glucosamine used, or the dose, frequency, or duration of use. Furthermore, the adults that reported glucosamine use also reported overall healthier lifestyle habits than those that were not taking glucosamine. A case-control study in Spanish patients found that glucosamine use is associated with 45% lower odds of ischemic stroke when compared with non-use; however, the benefit was only observed in patients taking glucosamine for 1 year or less (109643). This study did not clarify the form of glucosamine used or the dose or frequency of use. Furthermore, patients in the control group were generally healthier and less likely to have a history of cardiovascular disease, diabetes, or hyperlipidemia. Although both studies attempted to control for differences between patient populations, higher quality, prospective research is needed to clarify the relationship, if any, between glucosamine and stroke risk.
• Temporomandibular disorders (TMD). It is unclear if oral glucosamine sulfate is beneficial in patients with temporomandibular joint osteoarthritis. Details: A small and low-quality clinical study in patients with temporomandibular joint osteoarthritis shows that taking glucosamine sulfate 500 mg three times daily for 90 days seems to be no different than taking ibuprofen 400 mg three times daily for relieving pain and improving functional abilities such as chewing, yawning, talking, and laughing (3714). However, another small clinical study in patients with the same condition shows that taking glucosamine sulfate 1200 mg daily for 6 weeks does not improve pain or jaw opening capacity when compared with placebo (20105). Glucosamine sulfate has also been evaluated in combination with chondroitin for this condition. A meta-analysis of two small clinical studies in patients with TMD shows that taking glucosamine sulfate 1500 mg and chondroitin sulfate 1200 mg daily for 2 months does not reduce pain or increase maximum mouth opening when compared with tramadol 50-100 mg daily (109647). Other meta-analyses have reported similar results, however, these analyses may have been inadequately powered to detect a difference between groups (114572). Another small clinical trial in children aged 10-13 years with class II malocclusion shows that application of a specific combination gel product containing glucosamine, chondroitin, and essential oils (Jointace Gel, Vitabiotics) with an expander device, twice daily for 3 months does not improve temporomandibular space measures or pain or tension scores, when compared with placebo (110629).
• Wound healing. Although there is interest in using topical glucosamine for wound healing, there is insufficient reliable information about the clinical effects of glucosamine for this condition. More evidence is needed to rate glucosamine for these uses.

(Read more about GLUCOSAMINE)

POSSIBLY EFFECTIVE

• Dry eye. Applying eye drops containing hyaluronic acid alone or in combination with other ingredients, seems to improve symptoms of dry eye. Details: A large meta-analysis of clinical studies in patients with dry eye disease shows that using eye drops containing hyaluronic acid 0.1% to 0.4% for at least 14 days modestly improves tear production when compared with artificial tears or saline control, with a more significant improvement when compared with saline control. Tear stability is also modestly improved when compared with saline control (108622). Several individual clinical studies using specific hyaluronic acid eye drops have also demonstrated improvement. One clinical study in patients with dry eye disease shows that applying eye drops containing hyaluronic acid 0.1% to 0.3% 5-6 times daily for 12 weeks might improve symptoms to a similar degree as cyclosporine 0.05% eye drops. The products used in this study included Hyalein ophthalmic solution 0.1%, New Hyaluni ophthalmic solution 0.15%, and Hyaluni ophthalmic solution 0.3% (97885). Another clinical study shows similar efficacy between hyaluronic acid 0.15% eye drops (New Hyaluni), applied 6 times daily for 12 weeks, and eye drops containing cyclosporine 0.05% and carboxymethylcellulose 0.5%, applied twice daily (110555). A smaller clinical study in patients with dry eye disease shows that applying specific eye drops containing hyaluronic acid 0.2% (Hyalistil) seems to have similar efficacy as using tamarind seed polysaccharide eye drops (16301). Furthermore, adding hyaluronic acid to conventional treatment seems to offer additional benefit. A large multicenter clinical trial in patients with dry eye disease shows that applying 1-2 drops of artificial tears containing carboxymethylcellulose 0.5% and hyaluronic acid 0.1% (Optive Fusion, Allergan) at least 2 times daily for 3 months seems to further improve pain and discomfort when compared with using artificial tears containing carboxymethylcellulose alone (104384). One small clinical study also shows that hyaluronic acid 0.3% ocular gel and hyaluronic acid 0.18% eye drops, applied 4-6 times daily for 12 weeks, are equally effective for improving dry eye symptoms (110556). Hyaluronic acid has also been studied in combination with other ingredients. Several small clinical studies in patients with dry eye syndrome ranging from mild to severe shows that applying eye drops containing hyaluronic acid 0.2% or 0.3%, polyvinylpyrrolidone, and glycerin (Visaid 0.2% or 0.3%, Avizor S.A.), administered as one drop 3-8 times daily for one month, improves some signs and symptoms of dry eye when compared with sodium chloride 0.9% (97894,97895). Conversely, a large clinical study in patients with mild to moderate dry eye disease shows that applying preservative-free eye drops containing sodium hyaluronate with chondroitin sulfate (Humylub Ofteno PF, Laboratorios Sophia), one drop into each eye four times daily for 90 days, seems to be no different for improving dry eye severity when compared with using polyethylene/propylene glycol eye drops (104443).
• Venous leg ulcers. Topical application of hyaluronic acid-impregnated gauze reduces wound size and promotes wound healing. Details: Clinical studies in patients with at least one leg ulcer of venous or mixed arterial/venous origin show that once daily application of a specific hyaluronic acid-impregnated gauze (Ialuset, Laboratoires Genévrier) reduces wound size at 45 days by 73% and produces complete wound healing at or before 20 weeks in 40% of patients. In those receiving a neutral vehicle gauze, these improvements occurred in 46% and 19% of patients, respectively (108627,108640).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Aging skin. Oral hyaluronic acid has only been evaluated in combination with other ingredients; its effect when used alone is unclear. It is also unclear if topical hyaluronic acid is beneficial for aging skin. Details: A very small study shows that taking a specific combination product (GliSODin Skin Nutrients Advanced Anti-Aging Formula, Isocell North America Inc.) containing hyaluronic acid, krill oil, sea buckthorn berry oil, and cacao bean extract orally three times daily for 90 days, along with applying tazarotene 0.1% cream, moderately decreases wrinkling and photodamage and improves skin moisture and elasticity when compared with tazarotene cream alone (91778). Another small clinical study in females with aging skin shows that taking a specific combination product (BioCell Collagen, BioCell Technology, LLC) containing hyaluronic acid 100 mg, chondroitin sulfate 200 mg, and collagen peptides 600 mg daily for 12 weeks reduces lines and wrinkles by about 13% when compared with baseline (28681). The validity of this finding is limited by the lack of a comparator group. Furthermore, it should be noted that both studies were funded by the product manufacturer. A small open-label clinical study in females with mild to moderate lip dryness and mild to severe lip condition shows that three daily applications of a two-step lip treatment containing hyaluronic acid for 4 weeks improves the overall condition of lips, as well as texture/visual roughness, plumpness, color/rosiness, definition/contour, and lines/wrinkles when compared with baseline (108634). The validity of these findings is limited by the lack of a comparator group.
• Allergic rhinitis (hay fever). It is unclear if nasal irrigation with sodium hyaluronate is beneficial in patients with mild, persistent seasonal allergic rhinitis. Details: A small clinical study in patients with mild, persistent seasonal allergic rhinitis receiving an oral antihistamine and an intranasal corticosteroid shows that nasal irrigation with sodium hyaluronate twice daily for 1 month improves mucociliary clearance time by 3 minutes, compared with 1 minute with the use of isotonic saline and 5 minutes with the use of surfactant (108630). It is unclear if this change is associated with clinically relevant symptom improvement.
• Burns. It is unclear if topical hyaluronic acid is beneficial in patients with burns. Details: A meta-analysis of small clinical trials suggests that topical hyaluronic acid and hyaluronic acid derivatives might improve the healing of wounds, including burns, when compared with control (104389). A small nonrandomized clinical study in patients with partial- to full-thickness burns shows that hyaluronic acid 0.2% gel daily for 12 weeks during the re-epithelialization phase reduces erythema, tension, pruritus, burning, and neoangiogenesis when compared with baseline (108636). The lack of statistical comparison to the ozonated oil group and the single-blinded nature of the study limit the validity of these findings.
• Canker sores. It is unclear if topical hyaluronic acid is beneficial for canker sores. Details: A clinical study in adults with recurrent canker sores shows that applying a gel containing hyaluronic acid 0.2% two to three times daily for 7 days reduces soreness immediately and for up to 30 minutes after application when compared with baseline. However, these improvements are numerically similar to those seen with placebo (108637). The lack of statistical comparison to placebo limits the validity of this finding. A small observational study in children with recurrent canker sores has found that applying a gel containing hyaluronic acid 0.2% twice daily for 7 days is similarly effective to dexamethasone topical ointment applied three times daily for 5 days for reducing pain and ulcer size (104388).
• Corneal abrasion. It is unclear if eye drops containing hyaluronic acid are beneficial in preventing recurrence in patients with a history of traumatic corneal abrasion. Details: A small clinical study in patients with fully healed traumatic corneal abrasion at risk for recurrence shows that administration of eye drops containing hyaluronic acid 0.3% five times daily for 3 months does not reduce the incidence rate of major symptomatic episodes at 12 months when compared with observation alone (108623).
• Diabetic foot ulcers. Oral hyaluronic acid has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A meta-analysis of results from 4 clinical studies shows that applying hyaluronic acid combination gels or hyaluronic acid-based biomaterials to diabetic foot ulcers increases the odds of complete healing at 12 weeks by about 1.7-fold when compared to control treatment. Forms of hyaluronic acid assessed in the evaluated studies included zinc hyaluronate, hyaluronic acid-based biomaterial (Hyalograft 3D autograft), and a gel containing hyaluronic acid and amino acids (Vulnamin Gel, Errekappa) (91776). It is not clear if the beneficial effects were due to hyaluronic acid or other components of the treatments.
• Exercise-induced muscle soreness. Oral hyaluronic acid has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A very small clinical study in healthy, recreationally active adults shows that a specific product (BioCell Collagen, BioCell Technology, LLC) containing hyaluronic acid 150 mg, chondroitin sulfate 300 mg, and collagen peptides 900 mg, taken twice daily for 6 weeks prior to two bouts of resistance exercise, attenuates muscle damage and decreases delayed-onset muscle soreness when compared with placebo (96301). It is unclear if these effects are due to hyaluronic acid, the other ingredients, or the combination. Furthermore, it should be noted that both studies were funded by the product manufacturer.
• Gastroesophageal reflux disease (GERD). Oral hyaluronic acid has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Patients with non-erosive GERD are thought to be less responsive to conventional acid suppression with proton pump inhibiters (PPIs) and H-2 blockers. A small preliminary clinical study shows that taking a syrup containing hyaluronic acid and chondroitin sulfate along with PPIs, H2-receptor antagonists, and/or antacids, reduces the intensity of symptoms associated with non-erosive GERD by about 3.5-fold when compared with placebo (89592). A larger clinical study in patients with non-erosive GERD shows that taking a different formulation of the same combination of chondroitin sulfate and hyaluronic acid (Esoxx, Alfa Wassermann) 4 times daily for 14 days, in conjunction with a PPI, improves GERD symptom severity by 21%, heartburn by 15%, and regurgitation by 10% when compared with using a PPI and placebo (101271). Hyaluronic acid has also been evaluated in combination with chondroitin sulfate in patients with extraesophageal symptoms of GERD. A small, open-label study shows that taking a specific combination product (Gerdoff, SOFAR S.p.A.) containing hyaluronic acid and chondroitin sulfate three times daily with omeprazole 40 mg daily for 6 weeks increases the rate of treatment response, defined as a 50% or greater improvement in reflux symptoms index scores, by around 40% when compared with omeprazole alone. While average symptom scores were not significantly improved with the combination product over omeprazole, the need for omeprazole as rescue therapy for breakthrough symptoms was reduced in the treatment group (109648). It is unclear if the findings described above are due to hyaluronic acid, chondroitin sulfate, or the combination.
• Gingivitis. It is unclear if hyaluronic acid used in a mouthwash reduces gingivitis severity. Details: A small clinical study in patients with biofilm-induced gingivitis shows that rinsing with 10 mL of hyaluronic acid 0.025% mouth wash (Gengigel, RICERFARMA SRL) for 1 minute twice daily reduces probing index and bleeding when compared with rinsing with a placebo solution, but is less effective when compared with chlorhexidine 0.12% solution (104383). Another small clinical study in patients with plaque-induced gingivitis shows that rinsing with 10 mL of a mouthwash containing hyaluronic acid 0.1% and hydrogen peroxide 1.8% for 30 seconds twice daily for 21 days reduces gingival index scores but not plaque index scores when compared with placebo (110554). It is unclear if these findings are due to hyaluronic acid, hydrogen peroxide, or the combination.
• Intranasal surgery. It is unclear if topical hyaluronic acid irrigation improves recovery in patients after nasal surgery. Details: A small clinical study in patients that underwent nasal surgery for chronic rhinosinusitis shows that performing nasal irrigation with high molecular weight sodium hyaluronate 9 mg twice daily for 6 weeks improves sinus scarring, crusting, and headache when compared with nasal irrigation with saline. However, the sodium hyaluronate irrigation did not improve sinus inflammation or secretions, nasal obstruction, or facial pain (101288).
• Intrauterine adhesions. Several small studies suggest that intrauterine administration of hyaluronic acid gel seems to prevent intrauterine adhesions after uterine surgery. Details: Meta-analyses of 11-12 small clinical studies in patients undergoing uterine surgery shows that intrauterine application of 1-10 mL of hyaluronic acid gel after surgery reduces the risk of intrauterine adhesions by around 50% and increases pregnancy rates when compared with no treatment (110551,110552). One analysis suggests that hyaluronic acid is most effective for prevention of intrauterine adhesions when at least 5 mL of gel is applied (110551).
• Lichen planus. It is unclear if topical hyaluronic acid is beneficial in patients with oral lichen planus. Details: A clinical study in patients with oral lichen planus shows that application of a gel containing hyaluronic acid 0.2% four to five times daily for 28 days reduces soreness in as little as 5 minutes for up to 4 hours when compared with baseline. These findings are numerically similar to those seen with placebo; however, the lack of statistical comparison to placebo limits the validity of this finding (108635). A small clinical study in patients with symptomatic oral lichen planus (including mixed forms) shows that application of a gel containing hyaluronic acid 0.2% three times daily for 4 weeks is similarly effective to triamcinolone for improving pain, erythema, and lesion size (108633). It is unclear if the improvement from baseline differed between groups.
• Melasma. It is unclear if topical hyaluronic acid is beneficial in patients with moderate to severe facial melasma. Details: A small clinical study in patients with mostly mixed-type, moderate to severe facial melasma shows that twice daily application of hyaluronic acid along with isobutylamido thiazolyl resorcinol reduces melasma severity similarly to isobutylamido thiazolyl resorcinol alone (108628). The single-blinded nature of the study limits the validity of these findings.
• Oral mucositis. Topical hyaluronic acid has only been evaluated in combination with other ingredients; its effects when used alone is unclear. Details: A small clinical study in children aged 5 years or older with chemotherapy-induced oral mucositis shows that using a solution containing sodium hyaluronate, verbascoside, and polyvinylpyrrolidone (Mucosyte; Biopharm) three times daily is more effective than placebo for improving pain and other symptoms (97890). Another small clinical study in adults in recovery from hematopoietic stem cell transplantation shows that using a spray product containing sodium hyaluronate with synthetic amino acid precursors of collagen (Mucosamin) attenuates the development of severe oral mucositis when compared with chlorhexidine 0.2% (97889).
• Osteoarthritis. It is unclear if oral hyaluronic acid is beneficial in patients with osteoarthritis of the knee. Details: A small study in patients with knee osteoarthritis shows that taking chicken comb extract (Hyal-Joint, Bioibérica) 80 mg, standardized to contain hyaluronic acid 60% to 70%, once daily for 8 weeks does not reduce pain when compared with placebo (55742). This study was limited by small size and a significant placebo effect. Another small study in patients with knee osteoarthritis shows that taking a different supplement (Oralvisc, Bioibérica) 80 mg standardized to contain hyaluronic acid 70% and glycosaminoglycans once daily for 3 months modestly reduces pain when compared with placebo (91779). Reasons for these differing findings may relate to hyaluronic acid formulation, study funding sources, or the magnitude of placebo effect. Hyaluronic acid has also been studied in combination with chondroitin and collagen peptides (BioCell Collagen, BioCell Technology, LLC) with some evidence of benefit (28680).
• Otitis media. It is unclear if using intranasal hyaluronic acid solution is beneficial for otitis media in children. Details: Preliminary clinical research in children 3-12 years of age who have recurrent or chronic middle ear inflammation and adenoiditis shows that using a compound (Yabro, IBSA Farmaceutici Italia S.r.l.) containing hyaluronic acid in saline intranasally 15 days per month for 3 months modestly reduces the number of patients with impaired otoscopy or middle ear function when compared to baseline (97888). It is unclear if this effect is due to the hyaluronic acid product or to the natural resolution of inflammation over time.
• Radiation dermatitis. It is unclear if topical hyaluronic acid is beneficial for the prevention of radiation dermatitis. Details: A small clinical study in patients with breast cancer undergoing adjuvant radiation therapy following lumpectomy shows that three daily applications of a specific hyaluronic acid gel (RadiaPlex, MPM Medical) to one side of the breast results in a grade 2 or greater dermatitis occurrence rate of 62%, compared with a rate of 48% on the side receiving petrolatum-based gel. A review of a planned interim analysis led to early trial discontinuation (108638).
• Rhinosinusitis. It is unclear if hyaluronic acid solution is beneficial for acute or chronic rhinosinusitis when used in an intranasal saline rinse. Details: A small clinical study in adults with acute rhinosinusitis who are being treated with levofloxacin and prednisone shows that using a 3% hyaluronic acid in saline nasal douche twice daily improves smell, obstruction, and discharge within 14 days when compared with saline alone (97886). A very small clinical study in patients with chronic rhinosinusitis without nasal polyps shows that receiving micronized nasal hyaluronic acid douches twice daily for 30 days improves nasal symptoms, nasal obstruction, and ability to smell to a similar degree as normal saline (104387).
• Sexual dysfunction. It is unclear if vaginal hyaluronic acid is beneficial for improving sexual function in adults with dyspareunia. Details: A small nonrandomized clinical study in females with dyspareunia while taking oral hormonal contraceptives shows that once daily vaginal application of a hyaluronic acid gel for 12 weeks reduces pain and improves sexual function at 12 weeks when compared baseline. Though patients treated with twice weekly vaginal estrogen therapy had better 12-week scores than patients treated with hyaluronic acid, it is unclear if the improvements from baseline differed between groups (108639).
• Tooth extraction. It is unclear if topical hyaluronic acid is beneficial for wound healing after tooth extraction. Details: A small clinical study in patients undergoing tooth extraction shows that application of hyaluronic acid 0.2% gel or hyaluronic acid 0.1% spray to the extraction socket twice daily for 7 days increases the rate of wound closure when compared with no treatment (110553). The validity of these findings is limited by a lack of placebo control group.
• Urinary tract infections (UTIs). Oral and intravesical hyaluronic acid have been evaluated for the prevention of UTI in combination with other ingredients; its effect when used alone is unclear. Details: A meta-analysis of prospective and retrospective studies shows that intravesical administration of 50 mL of specific solutions containing chondroitin sulfate 2% and hyaluronic acid 1.6% (iAluRil, IBSA Farmaceutici; Cystistat, Bioniche), once weekly to once monthly for up to 6 months, reduces the rate of UTI recurrence by about 2-3 incidents per year and delays the time to the first UTI recurrence when compared with placebo or prophylaxis with sulfamethoxazole-trimethoprim (99688). However, the validity of these findings is limited by the low quality and high heterogeneity of the included studies, as well as concerns for publication bias. Also, the effect of hyaluronic acid alone is unclear. Oral hyaluronic acid has also been evaluated in combination with other ingredients for the prevention of recurrent UTI. A small prospective observational study shows that taking 1-2 capsules of a combination of hyaluronic acid, chondroitin sulfate, curcumin, and quercetin daily for 15 days each month, in conjunction with the use of local topical estrogen therapy for up to 12 months, reduces the number of women with recurrent UTIs when compared with taking the oral combination product or the vaginal estrogen product alone (96781). It is unclear if this effect is due to hyaluronic acid, other ingredients, or the combination.
• Vaginal atrophy. It is unclear if topical hyaluronic acid is beneficial for improving symptoms of vaginal atrophy. Details: A small, open-label clinical trial in patients going through menopause with symptoms of vaginal atrophy shows that applying 3 grams of a topical vaginal preparation of hyaluronic acid (Hyalo Gyn, Fidia Farmaceutici) every 3 days for 30 days improves vaginal health scores and reduces vaginal itching, vaginal burning, and pain during intercourse when compared to baseline. However, it does not appear to be any more effective than a polycarbophil vaginal gel (110549). Also, a small observational study in postmenopausal patients with vulvovaginal atrophy has found that applying a topical vaginal preparation containing hyaluronic acid (Justgin, JustPharma) three times weekly for 8 weeks is associated with improved symptoms of vaginal dryness, burning, and itching, as well as pain during intercourse, when compared to baseline (97887). The validity of these findings is limited by the lack of a comparator group and retrospective nature of the study. Some research has evaluated combination products containing hyaluronic acid for vaginal atrophy. A clinical trial in patients with cervical cancer shows that intravaginal administration of a specific suppository (Santes, Lo.Li. Pharma) containing hyaluronic acid, vitamin E, and vitamin A, once daily for the 5 week duration of radiotherapy reduces vaginal dryness, inflammation, and dyspareunia when compared with no additional treatment (101283). Also, a small, open-label clinical study in patients with vaginal atrophy after treatment for breast cancer shows that intravaginal application of a suppository containing hyaluronic acid and extract of aloe, marigold, tiger grass, and tea tree daily for 10 days then every 3 days for 80 days improves vaginal health scores and reduces vaginal dryness and pain during intercourse when compared to baseline, with no difference between the hyaluronic acid-containing suppository and vaginal laser therapy (110550). It is unclear if these findings are due to hyaluronic acid, other ingredients, or the combination.
• Wound healing. Small clinical studies show that topical hyaluronic acid and hyaluronic acid derivatives may improve the healing of various types of wounds. Details: A meta-analysis of small clinical trials suggest that topical hyaluronic acid and hyaluronic acid derivatives might improve the healing of burns, wounds, and skin ulcers when compared with control (104389). More evidence is needed to rate hyaluronic acid for these uses.

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LIKELY SAFE ...when used orally or intravenously and appropriately. Calcium is safe when used in appropriate doses (7555,12928,12946,95817). However, excessive doses should be avoided. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: Age 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg; 19-50 years, 2500 mg; 51+ years, 2000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stone, hypercalciuria, hypercalcemia, and milk-alkali syndrome. There has also been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these studies, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Advise patients not to consume more than the recommended daily intake of 1000-1200 mg per day and to consider total calcium intake from both dietary and supplemental sources (17484). Also, advise patients taking calcium supplements to take calcium along with vitamin D (93533).

POSSIBLY UNSAFE ...when used orally in excessive doses. The National Academy of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: 19-50 years, 2500 mg; 51 years and older, 2000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stones, hypercalciuria, hypercalcemia, and milk-alkali syndrome. There has also been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these studies, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Advise patients to not consume more than the recommended daily intake of 1000-1200 mg per day and to consider total calcium intake from both dietary and supplemental sources (17484). Also, advise patients taking calcium supplements to take calcium along with vitamin D (93533).

CHILDREN: LIKELY SAFE
when used orally and appropriately. Calcium is safe when used in appropriate doses (17506).

CHILDREN: POSSIBLY UNSAFE
when used orally in excessive doses. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stones, hypercalciuria, hypercalcemia, and milk-alkali syndrome.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately (945,1586,3263,3264,17506). The World Health Organization (WHO) recommends prescribing oral calcium supplementation 1.5-2 grams daily during pregnancy to those with low dietary calcium intake to prevent pre-eclampsia (97347).

PREGNANCY AND LACTATION: POSSIBLY UNSAFE
when used orally in excessive doses. The Institute of Medicine sets the same daily tolerable upper intake level (UL) for calcium according to age independent of pregnancy status: 9-18 years, 3000 mg; 19-50 years, 2500 mg (17506). Doses over these amounts might increase the risk of neonatal hypocalcemia-induced seizures possibly caused by transient neonatal hypoparathyroidism in the setting of excessive calcium supplementation during pregnancy, especially during the third trimester. Neonatal hypocalcemia is a risk factor for neonatal seizures (97345).

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LIKELY SAFE ...when used orally and appropriately. Chondroitin sulfate has been used safely in doses of up to 2000 mg daily for up to 6 years (1955,2533,13579,17732,22212,42339,42343,42348,42389,42396)(42398,42463,42477,42513,42520,42536,42541,89516,89558,89592)(89596,94360,94381,95788,95792). However, since chondroitin is often derived from bovine cartilage, historically, there was concern about contamination with diseased animal parts (1825). So far, there are no reports of disease transmission to humans due to use of contaminated chondroitin preparations. ...when used topically and appropriately as an ophthalmic viscosurgical device (OVD). Various products containing chondroitin sulfate and sodium hyaluronate have been granted approval by the US Food and Drug Administration (FDA) for use as an adjunct to cataract surgery (89436,89437).

POSSIBLY SAFE ...when used intramuscularly (10149,42397). ...when used topically as eye drops, short-term. Eye drops containing chondroitin sulfate with xanthan gum or glucosamine have been used with apparent safety four times daily for up to 3 months (89591,104443). ...when administered intravesically under the supervision of a physician (42338,42371,42373,42385,42387,42473,42511,42517,42519,109649).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

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LIKELY SAFE ...when glucosamine sulfate is used orally and appropriately. Glucosamine sulfate has been used safely in multiple clinical trials at a dose of 1000-1500 mg daily for 4 weeks to 3 years (2604,7026,8942,11340,12461)(14305,16717,89558,89567,94380,94382,95785).

POSSIBLY SAFE ...when glucosamine hydrochloride is used orally and appropriately. Glucosamine hydrochloride has been used with apparent safety at a dose of 1400-1600 mg daily for up to 2 years (4237,13579,14809,18344,42477,89516,89519,95784). Glucosamine hydrochloride 2 grams daily has also been used with apparent safety for up to 3 weeks (103281). ...when N-acetyl glucosamine is used orally and appropriately. N-acetyl glucosamine 100 mg daily has been used with apparent safety for up to 24 weeks (95795). ...when N-acetyl glucosamine is applied topically and appropriately. A 2% N-acetyl glucosamine cream has been safely used for up to 10 weeks (92721). ...when N-acetyl glucosamine is used rectally and appropriately. N-acetyl glucosamine 3-4 grams daily in 2 divided doses has been safely used (10234). ...when glucosamine sulfate is used intramuscularly and appropriately, short-term. Intramuscular glucosamine sulfate seems to be well tolerated when given twice weekly for up to 6 weeks (2605).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

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LIKELY SAFE ...when used orally and appropriately. Supplements standardized to contain hyaluronic acid 70%, in an 80 mg daily dose, have been used daily for up to 3 months with no reports of adverse effects (55742,91779). ...when used topically and appropriately. Hyaluronic acid, in a gel or impregnated gauze, has been safely applied to the skin in clinical trials (7889,7892,104389,108627,108640). ...when eye drop preparations containing up to 0.3% hyaluronic acid are used multiple times per day for up to 3 months (97885,97894,97895,110555).

PREGNANCY:
There is insufficient reliable information available about the safety of hyaluronic acid; avoid using.

LACTATION:
There is insufficient reliable information available about the safety of hyaluronic acid. It is not known if hyaluronic acid is excreted in breast milk (7890); avoid using.

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ALUMINUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Calcium citrate might increase aluminum absorption and toxicity. Other types of calcium do not increase aluminum absorption.  Details Calcium citrate can increase the absorption of aluminum when taken with aluminum hydroxide. The increase in aluminum levels may become toxic, particularly in individuals with kidney disease (21631). However, the effect of calcium citrate on aluminum absorption is due to the citrate anion rather than calcium cation. Calcium acetate does not appear to increase aluminum absorption (93006).

BISPHOSPHONATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Calcium reduces the absorption of bisphosphonates.  Details Advise patients to take bisphosphonates at least 30 minutes before calcium, but preferably at a different time of day. Calcium supplements decrease absorption of bisphosphonates (12937).

CALCIPOTRIENE (Dovonex) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Taking calcipotriene with calcium might increase the risk for hypercalcemia.  Details Calcipotriene is a vitamin D analog used topically for psoriasis. It can be absorbed in sufficient amounts to cause systemic effects, including hypercalcemia (12938). Theoretically, combining calcipotriene with calcium supplements might increase the risk of hypercalcemia.

CALCIUM CHANNEL BLOCKERS Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = D Intravenous calcium may decrease the effects of calcium channel blockers; oral calcium is unlikely to have this effect.  Details Intravenous calcium is used to decrease the effects of calcium channel blockers in the management of overdose. Intravenous calcium gluconate has been used before intravenous verapamil (Isoptin) to prevent or reduce the hypotensive effects without affecting the antiarrhythmic effects (6124). But there is no evidence that dietary or supplemental calcium when taken orally interacts with calcium channel blockers (12939,12947).

CEFTRIAXONE (Rocephin) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = D Co-administration of intravenous calcium and ceftriaxone can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys.  Details Avoid administering intravenous calcium in any form, such as parenteral nutrition or Lactated Ringers, within 48 hours of intravenous ceftriaxone. Case reports in neonates show that administering intravenous ceftriaxone and calcium can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys. In several cases, neonates have died as a result of this interaction (15794,21632). So far there are no reports in adults; however, there is still concern that this interaction might occur in adults.

DIGOXIN (Lanoxin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Using intravenous calcium with digoxin might increase the risk of fatal cardiac arrhythmias.  Details Hypercalcemia increases the risk of fatal cardiac arrhythmias with digoxin (12940). However, one retrospective analysis of clinical data suggests that intravenous calcium does not increase the risk of dysrhythmias or mortality in patients receiving digoxin (38960).

DILTIAZEM (Cardizem, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, calcium may reduce the therapeutic effects of diltiazem.  Details Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation (10574). Theoretically, calcium might increase this risk of hypercalcemia and reduce the effectiveness of diltiazem.

DOLUTEGRAVIR (Tivicay) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce levels of dolutegravir.  Details Advise patients to take dolutegravir either 2 hours before or 6 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium carbonate 1200 mg concomitantly with dolutegravir 50 mg reduces plasma levels of dolutegravir by almost 40%. Calcium appears to decrease levels of dolutegravir through chelation (93578).

ELVITEGRAVIR (Vitekta) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce levels of elvitegravir.  Details Advise patients to take elvitegravir either 2 hours before or 2 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium along with elvitegravir can reduce blood levels of elvitegravir through chelation (94166).

LEVOTHYROXINE (Synthroid, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce the absorption and effectiveness of levothyroxine.  Details Advise patients to take levothyroxine and calcium supplements at least 4 hours apart. Calcium reduces levothyroxine absorption, probably by forming insoluble complexes (5082). Calcium carbonate supplements reduce effectiveness of levothyroxine in patients with hypothyroidism (5081,5082,6137).

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use of calcium and lithium may increase this risk of hypercalcemia.  Details Clinical research suggests that long-term use of lithium may cause hypercalcemia in 10% to 60% of patients (38953). Theoretically, concomitant use of lithium and calcium supplements may further increase this risk.

QUINOLONE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Calcium seems to reduce the absorption of quinolone antibiotics.  Details Advise patients to take oral quinolones at least 2 hours before or 4-6 hours after calcium supplements or calcium-fortified foods. Taking calcium at the same time as oral quinolones can reduce quinolone absorption. Calcium binds to quinolones in the gut (4412,10339,21638,38570).

RALTEGRAVIR (Isentress) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Calcium may reduce levels of raltegravir.  Details Pharmacokinetic research shows that taking a single dose of calcium carbonate 3000 mg along with raltegravir 400 mg twice daily modestly decreases the mean area under the curve of raltegravir, but the decrease does not necessitate a dose adjustment of raltegravir (94164). However, a case of elevated HIV-1 RNA levels and documented resistance to raltegravir has been reported for a patient taking calcium carbonate 1 gram three times daily plus vitamin D3 (cholecalciferol) 400 IU three times daily in combination with raltegravir 400 mg twice daily for 11 months. It is thought that calcium reduced raltegravir levels by chelation, leading to treatment failure (94165).

SOTALOL (Betapace) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Calcium seems to reduce the absorption of sotalol.  Details Advise patients to separate doses by at least 2 hours before or 4-6 hours after calcium. Calcium appears to reduce the absorption of sotalol, probably by forming insoluble complexes (10018).

TETRACYCLINE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Calcium seems to reduce the absorption of tetracycline antibiotics.  Details Advise patients to take oral tetracyclines at least 2 hours before, or 4-6 hours after calcium supplements. Taking calcium at the same time as oral tetracyclines can reduce tetracycline absorption. Calcium binds to tetracyclines in the gut (1843).

THIAZIDE DIURETICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.  Details Thiazides reduce calcium excretion by the kidneys (1902). Using thiazides along with moderately large amounts of calcium carbonate increases the risk of milk-alkali syndrome (hypercalcemia, metabolic alkalosis, renal failure). Patients may need to have their serum calcium levels and/or parathyroid function monitored regularly.

VERAPAMIL (Calan, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, calcium may reduce the therapeutic effects of verapamil.  Details Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation (10574). Theoretically, use of calcium supplements may increase this risk of hypercalcemia and reduce the effectiveness of verapamil.

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WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Unlikely •  Level of Evidence = D Taking chondroitin in combination with glucosamine might increase the anticoagulant effects of warfarin. However, the effect of chondroitin alone is unclear.  Details There have been multiple reports of increased international normalized ratio (INR) in patients taking warfarin with glucosamine, with or without chondroitin. The lack of reports with chondroitin alone seem to suggest that the interactions occurring in these reports may have been due to glucosamine. In two individual case reports, glucosamine/chondroitin combinations were associated with a significant increase in INR in patients previously stabilized on warfarin (11389,16130). Additionally, 20 voluntary case reports to the US Food & Drug Administration (FDA) have linked glucosamine plus chondroitin with increased INR, bruising, and bleeding in patients who were also taking warfarin (16130). There have also been 20 additional case reports to the World Health Organization (WHO) that link glucosamine alone, without chondroitin, to increased INR in patients taking warfarin (16131).

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ACETAMINOPHEN (Tylenol, others) Interaction Rating = Minor Be watchful with this combination. Severity = Insignificant •  Occurrence = Possible •  Level of Evidence = B Acetaminophen might interfere with the activity of glucosamine sulfate by interacting with the sulfate portion.  Details Anecdotal reports suggest that adding glucosamine to an acetaminophen regimen might decrease pain control in patients with osteoarthritis (14806). Some research suggests that the sulfate portion of glucosamine sulfate might contribute to its effect in osteoarthritis. Since acetaminophen metabolism requires sulfur and reduces serum sulfate concentrations, acetaminophen could theoretically interfere with the action of glucosamine sulfate. Conversely, the administration of sulfate could theoretically decrease the effectiveness of acetaminophen in sulfate-deficient people by increasing its clearance (10313).

ANTIDIABETES DRUGS Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = B Despite initial concerns, it is unlikely that glucosamine will interfere with the effects of antidiabetes drugs.  Details In vitro and animal research has suggested that glucosamine might increase insulin resistance or decrease insulin production (371,372,3406,18342,18343). This has raised concerns that taking glucosamine might worsen diabetes and decrease the effectiveness of diabetes drugs. However, clinical research suggests that glucosamine does not have adverse effects on blood glucose or glycated hemoglobin (HbA1C) in healthy, obese, or type 2 diabetes patients (7026,7075,8942,10311,10317,15111).

TOPOISOMERASE II INHIBITORS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically glucosamine may induce resistance to topoisomerase II inhibitors.  Details In vitro research suggests that glucosamine might induce resistance to etoposide (VP16, VePesid) and doxorubicin (Adriamycin) by reducing inhibition of topoisomerase II, an enzyme required for DNA replication in tumor cells (7639). This effect has not been reported in humans.

WARFARIN (Coumadin) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = D Glucosamine might increase the anticoagulant effects of warfarin and increase the risk of bruising and bleeding.  Details In two individual case reports, glucosamine/chondroitin combinations were associated with a significant increase in international normalized ratio (INR) in patients previously stabilized on warfarin (11389,16130). In one case, the increase in INR occurred only after tripling the dose of a glucosamine/chondroitin supplement from 500 mg/400 mg daily to 1500/1200 mg daily (16130). Additionally, 20 voluntary case reports to the U.S. Food & Drug Administration (FDA) have linked glucosamine plus chondroitin with increased INR, bruising, and bleeding in patients who were also taking warfarin (16130). There have also been 20 additional case reports to the World Health Organization (WHO) that link glucosamine alone to increased INR in patients taking warfarin (16131). The mechanism of this interaction is unclear. Glucosamine is a small component of heparin, but is not thought to have anticoagulant activity; however, animal research suggests that it might have antiplatelet activity (16131).

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General ...Orally and intravenously, calcium is well-tolerated when used appropriately.
Most Common Adverse Effects:
Orally: Belching, constipation, diarrhea, flatulence, and stomach upset.
Serious Adverse Effects (Rare):
Orally: Case reports have raised concerns about calciphylaxis and kidney stones.

Cardiovascular ...There has been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these results, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Reasons for these discrepancies are not entirely clear. It may relate to whether calcium is taken as monotherapy or in combination with vitamin D. When taken with vitamin D, which is commonly recommended, calcium supplementation does not appear to be associated with an increased risk of CVD, CHD, or MI (93533,107231). Also, the association between calcium supplementation and CVD, CHD, or MI risk may be influenced by the amount of calcium consumed as part of the diet. Supplementation with calcium may be associated with an increased risk of MI in people with dietary calcium intake above 805 mg daily, but not in those with dietary calcium intake below 805 mg daily (17482). To minimize the possible risk of CVD, CHD, or MI, advise patients not to consume more than the recommended daily intake of 1000-1200 mg and to consider total calcium intake from both dietary and supplemental sources (17484). While dietary intake of calcium is preferred over supplemental intake, advise patients who require calcium supplements to take calcium along with vitamin D, as this combination does not appear to be associated with an increased risk of MI (93533).
Rarely, calcium intake can increase the risk of calciphylaxis, which usually occurs in patients with kidney failure. Calciphylaxis is the deposition of calcium phosphate in arterioles, which causes skin ulcers and skin necrosis. In a case report, a 64-year-old female with a history of neck fracture, sepsis, and ischemic colitis presented with painful leg ulcers due to calciphylaxis. She discontinued calcium and vitamin D supplementation and was treated with sodium thiosulfate and supportive care (95816).

Gastrointestinal ...Orally, calcium can cause belching, flatulence, nausea, gastrointestinal discomfort, and diarrhea (1824,1843,12950,38803). Although constipation is frequently cited as an adverse effect of calcium, there is no scientific substantiation of this side effect (1824,1843,1844,1845,12950,38978). Calcium carbonate has been reported to cause acid rebound, but this is controversial (12935,12936).

Oncologic ...There is some concern that very high doses of calcium might increase the risk of prostate cancer. Some epidemiological evidence suggests that consuming over 2000 mg/day of dietary calcium might increase the risk for prostate cancer (4825,12949). Additional research suggests that calcium intake over 1500 mg/day might increase the risk of advanced prostate cancer and prostate cancer mortality (14132). Consumption of dairy products has also been weakly linked to a small increase in prostate cancer risk (98894). However, contradictory research suggests no association between dietary intake of calcium and overall prostate cancer risk (14131,14132,104630). More evidence is needed to determine the effect of calcium, if any, on prostate cancer risk.

Renal ...Kidney stones have been reported in individuals taking calcium carbonate 1500 mg daily in combination with vitamin D 2000 IU daily for 4 years (93943).

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General ...Orally and topically, chondroitin sulfate is generally well tolerated. Intramuscular and ophthalmic use also seems to be well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, bloating, constipation, diarrhea, heartburn, nausea.
Serious Adverse Effects (Rare):
Orally: There have been rare reports of hepatotoxicity.

Cardiovascular ...One case of congestive heart failure and another case of myocardial infarction has been possibly attributed to use of glucosamine hydrochloride and chondroitin sulfate (13579,42477). Also, a case of mesenteric occlusion in one patient was considered possibly related to treatment with chondroitin sulfate and glucosamine (89520).

Dermatologic ...Orally, chondroitin sulfate has been associated with skin symptoms, such as eyelid edema, lower limb edema, alopecia, and skin rash (42513). Combinations of chondroitin sulfate along with glucosamine hydrochloride may also be associated with rash, water retention around eyes and scars, and hives on face, chest, torso, and legs when taken orally (42436,110628). A case of photosensitization that was reproducible with rechallenge has been reported following treatment with oral glucosamine-chondroitin products. However, it is not clear if this effect was due to glucosamine, chondroitin sulfate, or contaminants in the product (10408). A case of rash following treatment with intravesical chondroitin sulfate has been reported to be possibly related to the product (42385).

Gastrointestinal ...Orally, chondroitin might cause nausea, bloating, abdominal pain, diarrhea, constipation, vomiting, dyspepsia, and epigastric burning (42396,42436,42541,89561,110628,111647).

Genitourinary ...Intravesical chondroitin sulfate has been associated with cases of vulvar burning, vaginitis, urinary tract infection (UTI), dysuria, pelvic pain, and other bladder symptoms, such as increased frequency, urgency, or incontinence. However, these effects might be due to catheterization rather than chondroitin sulfate (42385,42387,42473).

Hematologic ...Concern has been expressed about possible anticoagulant activity of oral chondroitin sulfate. However, hematological changes have not occurred in patients taking chondroitin sulfate in clinical trials (760).

Hepatic ...Although relatively uncommon, combinations of glucosamine and chondroitin sulfate have been associated with acute liver injury that mimics autoimmune hepatitis. Two cases of elevated aminotransferase levels have been reported for patients taking glucosamine (form unspecified) and chondroitin sulfate at recommended doses. Aminotransferase levels, which were increased by four- to seven-fold, returned to normal following discontinuation of treatment (89515). Another case of abdominal pain, jaundice, fatigue, and elevated liver enzymes has been reported for a patient who used chondroitin sulfate (Condrosulf) for 2 years followed by a combination of glucosamine sulfate and chondroitin sulfate (Vita Mobility Complex) for 8 weeks. The patient required maintenance treatment with azathioprine to remain in remission (89518). A case of acute cholestatic hepatitis due to Glucosamine Forte, which contains glucosamine hydrochloride, chondroitin sulfate, Devil's claw, and shark cartilage, has been reported (89522). It is unclear whether these adverse events were related to chondroitin sulfate, other ingredients, or the combination.

Musculoskeletal ...Orally, chondroitin has been associated with musculoskeletal and connective-tissue events and disorders (13579,42520,95516).

Neurologic/CNS ...Rare cases of headache have been reported following treatment with products containing a combination of oral chondroitin sulfate and glucosamine hydrochloride or glucosamine sulfate (42436,89561). It is unclear if this effect was due to chondroitin, glucosamine, or the combination.
Patients should adhere to product directions when using chondroitin sulfate products that contain manganese. When taken at doses slightly higher than the recommended dose, these products can sometimes supply greater than the tolerable upper limit (UL) for manganese of 11 mg per day. Ingestion of more than 11 mg per day of manganese might cause significant central nervous system toxicity (7135).

Ocular/Otic ...A case of bilateral pinna chondritis (inflammation of the cartilage of the external ear) has been reported for a patient who received supplements containing glucosamine and chondroitin sulfate (42503).

Pulmonary/Respiratory ...A case of asthma exacerbation has been reported occurred following use of an oral glucosamine and chondroitin sulfate combination product (10002).

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General ...Orally, all forms of glucosamine seem to be well tolerated. Topically and rectally, N-acetyl glucosamine also seems to be well tolerated. Intramuscularly, glucosamine sulfate seems to be well tolerated. However, a thorough evaluation of safety outcomes has not been conducted for non-oral routes of administration.
Most Common Adverse Effects:
Orally: Bloating, constipation, cramps, diarrhea, heartburn, nausea.
Serious Adverse Effects (Rare):
Orally: There have been rare reports of severe allergic reactions and hepatotoxicity.

Cardiovascular ...One case of mesenteric occlusion in a clinical trial was considered possibly related to use of oral glucosamine hydrochloride and chondroitin sulfate (89520).
Some observational research has found that glucosamine use in patients with osteoarthritis is associated with a higher risk of cardiovascular disease (CVD) events when compared with non-use (109642). However, glucosamine users tended to be older, have multiple comorbidities, and be on antihyperlipidemic or antiplatelet therapy. Furthermore, other observational research in healthy adults has found that glucosamine use is associated with a reduced risk of fatal and non-fatal CVD events (99682). Higher quality, prospective research is needed to clarify the relationship, if any, between glucosamine and CVD risk.

Dermatologic ...Orally, glucosamine might cause skin reactions, including itching, rash, and erythema (2608,20084,89567,110628,113636). Also, fingernail and toenail toughening, with an increased rate of growth, has been reported (89572). Topically, N-acetyl glucosamine 2% with niacinamide 4% cream might cause rare skin reactions (92721). Photosensitization that was reproducible with re-challenge was reported in a case report of an individual using glucosamine (form unknown) and chondroitin (10408).

Endocrine ...Orally, glucosamine does not seem to impact blood glucose. Preliminary research and anecdotal reports have found that various forms of glucosamine might increase insulin resistance or decrease insulin production, increasing fasting plasma glucose levels (22,371,372,1203,3406,5059,7637,14810). This has raised concerns that taking glucosamine sulfate might worsen diabetes and decrease the effectiveness of diabetes drugs. However, clinical research suggests that various forms of glucosamine do not have adverse effects on blood glucose or glycated hemoglobin (HbA1C) in healthy, obese, patients with type 2 diabetes or impaired glucose tolerance (7026,7075,7638,8942,10311,10317,12107,14808,15111,89563).

Gastrointestinal ...Orally, glucosamine has been associated with gastrointestinal problems, including epigastric and abdominal pain, cramps, heartburn, diarrhea, nausea, dyspepsia, vomiting, constipation, and flatulence (1520,2608,16717,20084,20104,20105,89561,89562,89567,89568)(108897,110628,111647,113636). In older persons, use of glucosamine sulfate is associated with oral dryness (89564). In a clinical trial, a case of Helicobacter pylori gastritis was considered probably related to the use of glucosamine hydrochloride (89516).

Hepatic ...Although relatively uncommon, combinations of glucosamine and chondroitin sulfate have been associated with acute liver injury that mimics autoimmune hepatitis. Of 151 patients at an outpatient clinic for liver diseases, 23 acknowledged use of products containing glucosamine (form unspecified) and/or chondroitin. However, only 2 cases had an apparent relationship between transaminase elevation and the use of recommended doses of glucosamine and chondroitin sulfate. Aminotransferase levels, which were increased by four- to seven-fold, returned to normal following discontinuation of treatment (89515). In another case, a 65-year-old male presented to the hospital with signs and symptoms of drug-induced autoimmune hepatitis. The patient had used Condrosulf, containing chondroitin sulfate, for two years, followed by Vita Mobility Complex, containing chondroitin sulfate and glucosamine sulfate, for 8 weeks. The patient required maintenance treatment with azathioprine to remain in remission (89518). A case of acute cholestatic hepatitis due to Glucosamine Forte, which contains glucosamine hydrochloride, chondroitin sulfate, Devil's claw, and shark cartilage, has been reported (89522). It is unclear whether these adverse events were related to glucosamine, other ingredients, or the combination.

Immunologic ...There is some concern that glucosamine products might cause allergic reactions in sensitive individuals. One review of glucosamine-related adverse events in Australia found that 72% of all reports involved hypersensitivity reactions. Of these reactions, 35% were mild, including pruritis, urticaria, and lip edema, 49% were moderate, including dyspnea, and 16% were severe, including gait disturbance, somnolence, and hypotension. Anaphylaxis was reported in 1.5% of cases (102115). Also, in one clinical trial, a single patient developed allergic dermatitis considered to be likely due to glucosamine hydrochloride (89516). Glucosamine is derived from the exoskeletons of shrimp, lobster, and crabs. However, it is unclear if these adverse reactions were due to a shellfish sensitivity or general atopy. Additionally, shellfish allergies are caused by IgE antibodies to antigens in the meat of shellfish, not to antigens in the exoskeleton. Regardless, it is possible that some glucosamine products might be contaminated by this allergen during production (102115).

Neurologic/CNS ...Orally, glucosamine has been reported to cause drowsiness and headache (2608,89561,113636). Glucosamine plus chondroitin combination products that also contain manganese (e.g., CosaminDS) should always be taken according to product directions. When taken at doses slightly higher than the recommended dose, these products can sometimes supply greater than the tolerable upper limit (UL) for manganese which is 11 mg/day. Ingestion of more than 11 mg/day of manganese might cause significant central nervous system toxicity (7135).

Ocular/Otic ...In older persons, use of glucosamine sulfate has been associated with ocular dryness (89564). Increased intraocular pressure has occurred with glucosamine sulfate supplementation (89573,112460). Data from the FDA MedWatch adverse event reporting system shows that 0.21% of subjects taking glucosamine reported glaucoma, which is significantly greater than the 0.08% of subjects who reported glaucoma while using any other drug (112460).

Pulmonary/Respiratory ...Cases of asthma exacerbations associated with the use of glucosamine (form unknown)-chondroitin products have been reported (10002).

Renal ...Anecdotal reports have associated glucosamine with nephrotoxicity signals such as modestly elevated creatine phosphokinase and 1+ to 2+ proteinuria, but changes in kidney function have not been reported in long-term studies (7026,8942,10408,10409). It was also noted that effects may have been due to other concurrent medications or impurities in glucosamine-chondroitin products. Cases of acute interstitial nephritis induced by glucosamine (form unknown) have also been reported (89523).

Other ...There has been concern that glucosamine might increase the risk of metabolic disturbances resulting in increased cholesterol levels and blood pressure. However, glucosamine does not appear to increase the risk of these adverse effects. Taking glucosamine sulfate for up to 3 years does not significantly increase blood glucose or lipid levels, or cause any other disturbances in metabolism (7026,7075,8942,10311,10317).

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General ...Orally and topically, hyaluronic acid appears to be well tolerated.
Most Common Adverse Effects:
Topically: Eczema, erythema, itching, wound hemorrhage, wound infection (e.g., erysipelas).

Dermatologic ...The use of needle-free devices to inject hyaluronic acid for cosmetic purposes has been reported to cause serious injury, and in some cases permanent harm, to the skin, lips, and eyes (108613).
Topically, hyaluronic acid application has been reported to cause eczema, erythema, itching, wound hemorrhage, and wound infection (e.g., erysipelas) (108628,108640).

Ocular/Otic ...Ocular pain has been reported rarely in patients using eye drops containing up to 0. 3% hyaluronic acid (97885).

(Read more about HYALURONIC ACID)