Skin & hair
Peptides for skin and hair
Skincare peptides are almost never tested the way medicines are tested.
The evidence mix
The 11 peptides on this page, by how well they have been tested.
- Approved medicinenone on this page
- Still being tested in peoplenone on this page
- Tested in people, but barely9 peptides
- Only tested on animals1 peptide
- No real evidence at all1 peptide
Seven of the eleven entries here rest on small, short studies, several of them run or paid for by the company selling the ingredient, and an eighth has no published study at all. A cosmetic claim does not have to prove a clinical effect before it can be printed on the box. The last three are not skincare ingredients in any ordinary sense. One is an unapproved injection sold online to darken skin without sunlight, whose entire tanning evidence is a pilot study in three men and whose reported harms have made several national regulators warn against it by name. One is a three-amino-acid fragment sold for inflamed skin that has never been given to a person in a published study at all. And one is a supplement sold to do the opposite of the first — lighten skin — whose largest placebo-controlled trial found nothing at all, and whose drip form regulators have publicly warned against.
All 11 peptides on this page
Strongest evidence first.
Tested in people, but barely
Human studies exist, but they are small, short, uncontrolled, paid for by the seller, or they measure something easy to measure instead of something that matters.
9 peptides
- Evidence level 3 of 5: Tested in people, but barely
Acetyl hexapeptide-8
Argireline · acetyl hexapeptide-3
Sold in skincare for expression lines and wrinkles.
The studies are small and short, and one independent trial finished without publishing results.
Sold as: Skincare
- Evidence level 3 of 5: Tested in people, but barely
Collagen peptides (hydrolysed collagen)
hydrolysed collagen · collagen hydrolysate
Sold as a supplement for skin, hair, bones and joints.
Small human trials report some skin and joint changes, but many were funded by the industry selling the products.
Sold as: Supplement
- Evidence level 3 of 5: Tested in people, but barely
GHK-Cu (copper tripeptide-1)
Copper Tripeptide-1 (INCI) · copper peptide
Sold in skincare for wrinkles, skin repair and hair growth.
Human studies are small, and the only blinded objective measurement found no clear benefit.
Sold as: Skincare
- Evidence level 3 of 5: Tested in people, but barely
Glutathione
GSH · L-glutathione
Sold as an antioxidant supplement, and as a drip into a vein for lightening skin.
Most of a swallowed dose is broken down before it reaches the blood, the placebo-controlled skin trials are small and disagree, and the drip has no adequate trial behind it.
Sold as: Supplement
- Evidence level 3 of 5: Tested in people, but barely
Melanotan II
Melanotan 2 · MT-II
Sold online as a tanning injection, and separately as something that produces erections.
Two placebo-controlled studies in 20 men found it produces erections; the tanning evidence is one pilot in three men, and the harms are single case reports.
Sold as: Gray market
- Evidence level 3 of 5: Tested in people, but barely
Palmitoyl pentapeptide-4
Matrixyl · pal-KTTKS
Sold in anti-wrinkle skincare.
The main human study was small and linked to the ingredient's commercial development.
Sold as: Skincare
- Evidence level 3 of 5: Tested in people, but barely
Palmitoyl tetrapeptide-7
pal-GQPR · Rigin
Sold in skincare blends for wrinkles and irritated-looking skin.
No peer-reviewed human study has tested this ingredient on its own.
Sold as: Skincare
- Evidence level 3 of 5: Tested in people, but barely
Palmitoyl tripeptide-1
pal-GHK · Biopeptide CL
Sold in skincare to support collagen and soften wrinkles.
The evidence comes from two small experiments submitted by the raw-material supplier.
Sold as: Skincare
- Evidence level 3 of 5: Tested in people, but barely
SNAP-8
Acetyl octapeptide-3 · Acetyl Octapeptide-3 (INCI)
Sold in skincare for expression lines and wrinkles, as the longer version of Argireline.
No published study has tested it on its own, and the wrinkle percentages it is sold on come from the ingredient maker.
Sold as: Skincare
Only tested on animals
The evidence is animal experiments, cells in a dish, or computer models. No meaningful controlled trial in humans has been published.
1 peptide
No real evidence at all
Nothing published worth citing, in any species. What circulates is anecdote, sales material, or a guess extrapolated from something else.
1 peptide