Peptides for skin and hair
11 peptides
Skincare peptides are almost never tested the way medicines are tested. 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.
- Tested in people, but barely
Acetyl hexapeptide-8
Argireline · acetyl hexapeptide-3
Category SkincareSold in skincare for expression lines and wrinkles.
The studies are small and short, and one independent trial finished without publishing results.
- Tested in people, but barely
Collagen peptides (hydrolysed collagen)
hydrolysed collagen · collagen hydrolysate
Category SupplementSold 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.
- Tested in people, but barely
GHK-Cu (copper tripeptide-1)
Copper Tripeptide-1 (INCI) · copper peptide
Category SkincareSold in skincare for wrinkles, skin repair and hair growth.
Human studies are small, and the only blinded objective measurement found no clear benefit.
- Tested in people, but barely
Glutathione
GSH · L-glutathione
Category SupplementSold 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.
- Tested in people, but barely
Melanotan II
Melanotan 2 · MT-II
Category Gray marketSold 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.
- Tested in people, but barely
Palmitoyl pentapeptide-4
Matrixyl · pal-KTTKS
Category SkincareSold in anti-wrinkle skincare.
The main human study was small and linked to the ingredient's commercial development.
- Tested in people, but barely
Palmitoyl tetrapeptide-7
pal-GQPR · Rigin
Category SkincareSold in skincare blends for wrinkles and irritated-looking skin.
No peer-reviewed human study has tested this ingredient on its own.
- Tested in people, but barely
Palmitoyl tripeptide-1
pal-GHK · Biopeptide CL
Category SkincareSold in skincare to support collagen and soften wrinkles.
The evidence comes from two small experiments submitted by the raw-material supplier.
- Tested in people, but barely
SNAP-8
Acetyl octapeptide-3 · Acetyl Octapeptide-3 (INCI)
Category SkincareSold 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.
- Only tested on animals
KPV
KPV peptide · Lys-Pro-Val
Category Gray marketSold for gut inflammation, skin conditions and wound healing.
No published study has ever given it to a person; the evidence is mouse, rat and rabbit experiments and cells in dishes.
- No real evidence at all
Acetyl tetrapeptide-5
Eyeseryl · Acetyl Tetrapeptide-5 (INCI)
Category SkincareSold in eye creams for puffiness and dark circles.
No peer-reviewed clinical study of this ingredient has been published.