What are collagen peptides?
Collagen peptides are collagen protein broken into small pieces (hydrolyzed) so they dissolve easily and are absorbed better. They are sold as powders, capsules and drinks, made from cow, pig, fish or chicken collagen.
Collagen is the main structural protein in skin, bones, tendons and cartilage.
What do collagen peptides do?
After digestion, some small collagen pieces reach the blood and are thought to signal skin and joint cells to make more collagen. They also supply amino acids, like glycine and proline, that collagen is built from.
What does the research on collagen peptides show?
Meta-analyses of randomized trials find modest improvements in skin hydration and elasticity, mostly after 8 to 12 weeks. Results seem to depend more on how long people take them than on the amount.
One 2025 analysis found that studies funded by supplement companies reported benefits, while independent studies did not. Evidence for joints, hair and nails is weaker.
Collagen peptides side effects and risks
Collagen peptides are generally well tolerated; some people report bloating, heartburn or a lingering taste. Check the source if you have fish, shellfish or egg allergies, and choose third-party-tested products, since supplements aren’t checked by the FDA.
Are collagen peptides legal?
Yes. Collagen peptides are sold legally as dietary supplements in the US.
The FDA doesn’t check supplements for effectiveness before they are sold.