Peptides for skin: creams, injections and the evidence

Peptides in skin care are ingredients in creams and serums, such as palmitoyl pentapeptide, acetyl hexapeptide-8 and the copper peptide GHK-Cu. The studies behind them are mostly small and short, and several were run by the companies that make them; the best ones show modest effects on fine lines. Injected peptides sold for skin, such as GHK-Cu injections or melanotan II for tanning, are unapproved drugs with real safety concerns.

What do peptides do in skin care?

Each cosmetic peptide is designed for a job, such as signaling skin cells or damping a nerve signal. A review of topical peptides grouped them into four families by how they are meant to work: signal peptides, enzyme-inhibitor peptides, neurotransmitter-inhibitor peptides and carrier peptides (Gorouhi and Maibach, 2009).

Three you will see on ingredient lists:

• Palmitoyl pentapeptide (pal-KTTKS) was designed as a topical ingredient to stimulate collagen production (Robinson et al., 2005).
• Acetyl hexapeptide-8 was designed to imitate, much more weakly, how botulinum toxin relaxes expression lines (Blanes-Mira et al., 2002).
• GHK-Cu is a naturally occurring three-amino-acid peptide bound to copper. In lab and animal studies it increases collagen and supports tissue repair (Pickart and Margolina, 2018).

What does the research show?

Palmitoyl pentapeptide. In a 12-week split-face trial, 93 women applied a moisturizer with the peptide to one side of the face and the same moisturizer without it to the other. The peptide side showed significantly more reduction in wrinkles and fine lines. The authors worked for Procter & Gamble (Robinson et al., 2005).

Acetyl hexapeptide-8. The original study reported up to 30% shallower wrinkles after 30 days (Blanes-Mira et al., 2002). A 2025 review notes that the peptide penetrates skin poorly and that whether it reaches the nerve-muscle junction, where it would need to act, “remains uncertain” (Zdrada-Nowak et al., 2025).

GHK-Cu. A 2026 systematic review found 20 studies, of which 18 were in cells or animals and only 2 were randomized trials in people. Those trials reported better satisfaction after laser resurfacing and smaller wrinkle volume and depth, but the authors call the clinical evidence limited (Mokhtar et al., 2026). A second 2026 review judged the clinical evidence sparse and noted that a 13-person study after laser treatment was negative on objective measures (Mateescu et al., 2026).

The honest summary: some peptide creams have small trials showing modest improvement in fine lines over weeks. None has long-term data, few trials are independent, and results from one peptide or one formula don’t carry over to another.

Why cosmetics don’t need FDA approval

Cosmetic products and ingredients, apart from color additives, do not need FDA approval before they are sold. Drugs generally do. The FDA also says the term “cosmeceutical” has no meaning under the law: a product is a cosmetic, a drug, or both (FDA).

So a peptide serum on a store shelf has not been reviewed by the FDA for whether it works. Its claims should stay within appearance. The FDA gives “regenerate cells” as an example of a claim that makes a product a drug.

Injected peptides for skin

Injections are a different matter. An injected product is used as a drug, and none of the peptides below is FDA-approved for skin.

• GHK-Cu injections. The FDA warns that compounded injectable GHK-Cu may cause immune reactions because of aggregation and peptide-related impurities, and that human data are limited (FDA). Non-injectable GHK-Cu is back under evaluation for pharmacy compounding, and the FDA plans to discuss it with an advisory committee before the end of February 2027 (FDA).
• Melanotan II is sold for tanning. Published case reports describe melanoma, a brain swelling disorder, an overstimulated adrenaline-like state and painful prolonged erections in people using it (FDA). A review found reports of new or changing moles and melanomas, and several national health agencies have issued warnings (Habbema et al., 2017).

US regulatory status

• GHK-CuUS status: Cosmetic

  GHK-Cu is sold mainly in cosmetics, which don’t need FDA approval, and no GHK-Cu drug is FDA-approved. Injectable GHK-Cu is not on any list that allows pharmacy compounding, and the FDA has flagged it for possible immune reactions. Non-injectable GHK-Cu was put back in Category 1 in May 2026, ahead of an FDA advisory committee review planned before the end of February 2027.

  As of October 16, 2026

  Sources191014

• Melanotan IIUS status: Not approved

  Melanotan II is not approved by the FDA for any use, and it is a different drug from afamelanotide (Scenesse), an implant approved for erythropoietic protoporphyria. The FDA’s compounding safety page cites case reports of melanoma, PRES, sympathomimetic toxidrome and priapism, and an FDA import alert covers melanotan products sold online. The FDA plans to discuss melanotan II with an advisory committee before the end of February 2027.

  As of October 16, 2026

  Sources9141516

Do collagen peptide supplements help skin?

Probably not, on current evidence. A 2025 meta-analysis of 23 randomized trials found that collagen supplements improved skin hydration, elasticity and wrinkles overall, but the benefit disappeared in trials not funded by industry and in high-quality trials. The authors concluded there is “no clinical evidence to support the use of collagen supplements to prevent or treat skin aging” (Myung et al., 2025).

Collagen peptides are sold as dietary supplements, which the FDA does not approve before they are marketed (FDA).

Questions people ask