Do collagen supplements work? What trials show for skin and joints

Collagen has become one of the biggest names in the supplement aisle, sold as powders, gummies and drinks that promise firmer skin, fewer wrinkles and easier joints. Collagen is the main structural protein in skin, tendons and cartilage, so the idea of topping it up sounds intuitive.

The trials tell a more complicated story. Pooled together, they suggest modest benefits for skin. But a 2025 analysis that sorted the trials by who paid for them and how well they were done found the benefits disappeared in the independent and higher-quality studies.

What collagen supplements are

Most collagen supplements contain hydrolyzed collagen, collagen broken into small protein fragments, usually from cattle, pigs or fish. Like any protein, it is digested in the gut. The question the trials try to answer is whether taking it by mouth changes skin or joints in ways people can notice.

One review notes that oral hydrolyzed collagen (HC) supplementation is widely recommended for improving age-related skin changes, while clinical evidence remains inconsistent. In the US, supplements are regulated differently from medicines: supplement firms are responsible for evaluating the safety and labeling of their products before marketing, and the Food and Drug Administration does not approve them before sale.

What pooled collagen skin trials show

The 2025 analysis, in The American Journal of Medicine, included a total of 23 RCTs with 1474 participants, randomized controlled trials comparing collagen with placebo. Taken together, collagen supplements significantly improved skin hydration, elasticity, and wrinkles.

A separate 2026 review of 25 trials came to a similar first impression. Collagen outperformed placebo for skin hydration in 10 of 15 trials, elasticity in 10 of 13 and wrinkle depth or volume in 9 of 10. But its authors also noted that the majority of included trials were rated as having a high risk of bias, and called the evidence preliminary.

That review also looked at quality of life. Seven trials measured it, mostly in people with osteoarthritis or rheumatoid arthritis, and the results varied depending on the questionnaire and the group studied. Trial sizes ranged from 13 to 236 participants, and seven of the 25 trials enrolled people with chronic diseases rather than healthy volunteers, which makes the results harder to apply to the typical buyer of a beauty supplement.

Why funding and study quality change the collagen answer

The 2025 analysis went a step further and split the trials. In the subgroup analysis by funding source, studies not receiving funding from pharmaceutical companies revealed no effect of collagen supplements on hydration, elasticity or wrinkles, while industry-funded studies did show effects.

Study quality told the same story. High-quality studies revealed no significant effect in all categories, meaning no difference large enough to rule out chance, while low-quality studies showed an improvement in elasticity. When a benefit appears mainly in the weakest and most commercially interested studies, it is a warning sign that the pooled result may be inflated.

The authors’ conclusion was blunt: there is currently no clinical evidence to support the use of collagen supplements to prevent or treat skin aging.

What about collagen for joints?

Joint claims rest on a smaller evidence base, mostly in people with osteoarthritis. A 2018 meta-analysis of placebo-controlled trials found collagen treatment showed a significant reduction in the score of total WOMAC index, a standard osteoarthritis questionnaire, by about 8 points, and improved stiffness.

The pain and physical function parts of that questionnaire did not change clearly, which are the parts that matter most to people with arthritis. A separate pain scale did improve, by about 17 points on a 100-point line, though that sits awkwardly beside the questionnaire’s pain score, which did not move. Differences like that often reflect small trials measuring things in different ways. The picture is of modest, inconsistent effects from a limited number of trials, which have not been assessed by funding source in the same way as the skin trials.

What the collagen research cannot tell us

Most collagen trials were small, with as few as 13 participants, and short, often 8 to 12 weeks. They used different products, doses and ways of measuring skin, which makes them hard to compare. Many were sponsored by manufacturers.

Almost none tested whether effects last, whether people could see a difference in the mirror, or how collagen compares with getting protein from food. Long-term safety data are limited, although the trials reported few side effects.

What the collagen evidence adds up to

For skin, the most rigorous and independent trials do not show a benefit, and the 2025 analysis found no clinical evidence to support collagen for skin aging. For osteoarthritis, there are hints of modest improvement in stiffness and overall scores, but not clearly in pain or function.

Collagen appears to be well tolerated. HC supplementation was generally well-tolerated, with a low incidence of adverse events, in the 2026 review, so the main risk for most buyers is spending money on an effect that may not exist. The gap between the marketing and the independent evidence is the main thing the research shows, and larger, independent, longer trials would be needed to settle whether there is any real effect.