Glucosamine and Chondroitin

What it is

Glucosamine sulfate and chondroitin sulfate, often from bovine cartilage, are sold as supplements for joint pain. A common product pairs 1,500 mg of glucosamine sulfate with 1,200 mg of bovine chondroitin sulfate a day [1].

What the research says

Several meta-analyses of placebo-controlled trials found small pain relief. In a 2018 meta-analysis, glucosamine reduced knee pain on a visual scale by about 7 mm more than placebo, and chondroitin by about 8 mm; the combination did not [2]. A 2024 meta-analysis of 25 trials found chondroitin reduced pain and improved physical function, and that glucosamine slowed joint space narrowing [3]. A Cochrane review of chondroitin found pain about 8 points better on a 0 to 100 scale in trials of up to six months, but rated the evidence as low quality [4].

The largest trial, GAIT, found no significant difference from placebo in the share of people with a 20% drop in pain over 24 weeks [5]. Over two years, no treatment reached a clinically important difference in pain or function [6]. A 2010 network meta-analysis estimated pain differences below its threshold for a meaningful change [7].

For joint damage, one two-year trial found the combination slowed joint space narrowing by 0.10 mm more than placebo [8].

Doses used in studies

GAIT used 1,500 mg of glucosamine and 1,200 mg of chondroitin sulfate a day, over 24 weeks [5]. The two-year follow-up used glucosamine 500 mg and chondroitin 400 mg, each three times a day [6]. These are doses from trials, not recommendations.

Safety and interactions

Adverse events in GAIT were mild, infrequent and evenly spread across groups [5]. Headache and changes in glucose tolerance were the most common treatment-related side effects in a 24-week trial of a glucosamine and chondroitin product [1]. Across 69 trials of supplements for osteoarthritis, safety outcomes did not differ from placebo, except for diacerein [9]. People taking blood sugar medicines should ask a doctor before use, given the glucose changes seen in a trial [1].

The studies reviewed did not report an upper intake limit or a toxic dose [5][1]. None of the studies reviewed reported on pregnancy or breastfeeding [5][1]. The abstracts reviewed did not report outcomes for people with kidney, liver or bleeding disorders [5][1].

Caveats and open questions

The evidence is mixed. Meta-analyses that found small pain relief included trials of variable quality, and the Cochrane chondroitin review rated its evidence as low quality [4]. The lead author of the Cochrane chondroitin review reported research grants from pharmaceutical companies [4]. A 2010 review found industry-funded trials showed larger effects than independent ones [7]. The combination of glucosamine and chondroitin is the most debated: it was not better than placebo overall in GAIT, but did better in people with moderate to severe pain, an exploratory finding [5]. The 2021 review found the long-term benefit clinically questionable, so whether it holds over years is unclear [10].