800–1,200 mg/day, sustained for several weeks.
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Chondroitin sulfate is a natural high-molecular-weight glycosaminoglycan that forms part of the extracellular matrix of cartilage, tendons, and intervertebral discs; together with glucosamine, it has for decades been one of the best-selling supplements for osteoarthritis, with an enormous volume of clinical research and results that have gone through phases of initial optimism, methodological skepticism, and nuanced reassessment as increasingly rigorous trials have been published.
The chondroitin used in clinical research is usually extracted from bovine, porcine, or shark cartilage, and its purity and molecular weight vary enormously among commercial products; European pharmaceutical products with pharmaceutical-grade chondroitin sulfate (Condrosulf, Structum) are the ones that have generated most of the positive data in rigorous clinical trials, whereas generic supplements on the market have very uneven quality and less predictable efficacy.
The MOVES trial (Multicentre Osteoarthritis interventionVE Study), published in 2016, compared chondroitin 1,200 mg/day plus glucosamine 1,500 mg/day versus celecoxib 200 mg/day for 6 months in 606 patients with symptomatic knee osteoarthritis: the supplement combination showed efficacy comparable to the reference anti-inflammatory in reducing pain and improving function, with a better tolerability profile.
Other meta-analyses and later trials have confirmed a modest but significant effect of chondroitin alone on joint pain and function in knee and hip osteoarthritis, with the important caveat that European pharmaceutical products show more consistent results than generic supplements on the U.S. market, possibly because of differences in purity, molecular weight, and standardization.
A relevant clinical question is whether chondroitin, in addition to relieving symptoms, can slow the structural progression of osteoarthritis (measured by joint space narrowing on radiographs or by cartilage volume loss on MRI); several 2-3-year trials have suggested a modest effect on the rate of radiographic progression, which would distinguish it from anti-inflammatories that only modify symptoms.
These data on structural modification are what led several European guidelines (EULAR, ESCEO) to classify chondroitin as a SYSADOA (symptomatic slow-acting drugs for osteoarthritis), a category that recognizes its effect on symptoms and possible disease modification; American guidelines (ACR) are more conservative and do not formally recommend it, reflecting regulatory differences and differences in the interpretation of the evidence.
The combination of chondroitin + glucosamine (typically 1,200 mg + 1,500 mg/day) is the most widely used in the real world, partly out of commercial habit and partly because of the logic of combining two structural components of cartilage; direct trials comparing the combination vs. each one separately do not show a clear additive superiority, but the combination is the one with the best evidence under real-world clinical conditions.
The doses studied range from 800 to 1,200 milligrams daily of chondroitin sulfate, divided into two or three doses with meals; the clinical effect typically appears between 4 and 8 weeks and is maintained as long as treatment lasts, with no dependence or rebound syndrome on discontinuation; it is advisable to choose European pharmaceutical products or standardized supplements from brands with clinical backing.
Generally well tolerated; the most common adverse effects are mild digestive discomfort, occasionally headache and, rarely, eyelid edema or skin rashes; people taking warfarin should be cautious because of a described interaction (potentially enhancing the anticoagulant effect), and people with bronchial asthma may experience worsening in sensitive cases; the shark cartilage source raises environmental issues that should be considered when choosing the product.
Information, not medical advice. Scientific evidence reflects the quality of the studies.