Does collagen help your joints and muscles?

Short answer

Not for muscle. Collagen's muscle gains came from simply eating more protein, and the same amount of whey built more muscle. For joints, it eased knee pain during exercise a little more than a dummy pill.

Does collagen help your joints and muscles?
'Eat collagen → more collagen in your body → better joints and muscles' — does this formula hold?
Joints, tendons and skin are made of collagen. So people say eating collagen goes straight to your joints and muscles. We checked joints, muscles and tendons in turn.
Knee arthritis pain went down
11 trials, 870 people: better than a dummy pill
A 2024 analysis that pooled 11 trials with 870 people with knee arthritis found that those taking collagen improved more in pain and movement scores than those on a dummy pill. For people whose joints were already worn, it worked.
What about knees that hurt during exercise?
180 people: 5 g a day eased pain a little more in 12 weeks
180 people with knee pain during exercise took 5 g a day for 12 weeks. Their pain score dropped 21.9 points out of 100. The dummy-pill group also dropped 15.6 points, so the gap was small, about 6 points, and in a trial of 167 people taking 10 g a day, even that gap was gone.
Did muscle grow more?
768 people: lean mass rose more
A 2024 analysis that pooled 19 studies with 768 people who trained and took collagen for over 8 weeks found that lean mass (muscle and everything except fat) and strength rose more than with a dummy pill. But the dummy pills in these trials had no protein at all (silica or maltodextrin powder).
So how does it compare with another protein?
At the same 35 g, whey built more muscle
22 people trained for 10 weeks taking 35 g of whey or collagen. Leucine, the amino acid that switches on muscle building, was matched at 3 g. Thigh muscle thickness grew 8.4% with whey and 5.6% with collagen; the arm grew 10.1% and 6.0%. Strength rose about the same.
Tendons did get a bit thicker
But it added nothing to strength
50 people did heavy leg training for 14 weeks with 5 g a day, and their knee tendon thickened more than with a dummy pill. Muscle size and strength were the same in both groups. A 2026 review of 8 trials with 257 people also found thicker tendons but no extra strength.
Bottom line: protein for muscle, a little for joints
The 'collagen → muscle' link was really 'protein → muscle'
Collagen's muscle gains came from eating more protein, and the same amount of whey did better. Knee pain during exercise eased a little more with 5 g a day than with a dummy pill. If muscle is the goal, filling that share with ordinary protein like meat, eggs or whey works.