Peptides in skincare: what the trials and labels show

What can peptides do for the skin?

A 2025 review counted 102 peptides sold for cosmetics, most of them inspired by molecules already found in the human body⁶. It says the lab and skin-sample data behind them are of “divergent levels”⁶. This guide covers peptides put on the skin. Our skin ranking covers GHK-Cu, glutathione and the tanning peptides. Our collagen peptides guide covers supplements taken by mouth, and What are peptides? explains the basics.

Another 2025 review sorts cosmetic peptides into four classes by their intended job⁷.

• Signal peptides are meant to prompt fibroblasts, the skin cells that make collagen, to make more; an example is palmitoyl pentapeptide-4, sold as Matrixyl⁷.
• Neurotransmitter-inhibitor peptides are meant to relax the facial muscles behind expression lines; examples are acetyl hexapeptide-3, sold as Argireline, and pentapeptide-18, sold as Leuphasyl⁷⁸.
• Carrier peptides deliver trace elements; copper tripeptide-1, the label name for GHK-Cu, is the review’s example⁷⁴⁷.
• Enzyme-inhibitor peptides, such as soybean, rice and silk peptides, are meant to slow collagen breakdown⁷. The review says there are not enough clinical studies to confirm their benefits⁷.

The same molecule can appear under a label name and a trade name²⁸.

• Matrixyl is palmitoyl pentapeptide-4, also listed as palmitoyl pentapeptide-3 or pal-KTTKS: the peptide KTTKS joined to palmitic acid, a fatty acid²⁹.
• Matrixyl 3000 contains palmitoyl tripeptide-1 (pal-GHK) and palmitoyl tetrapeptide-7 (pal-GQPR)¹⁰. PubChem also lists palmitoyl oligopeptide, a retired name, for the first and palmitoyl tetrapeptide-3 for the second¹¹¹².
• Argireline, from the Barcelona company Lipotec, is acetyl hexapeptide-8⁸. Acetyl hexapeptide-3 is a retired name for the same ingredient⁹.

Reviews disagree about how strong the evidence is¹³¹⁴. A 2017 review said clinical evidence for efficacy “is often weak”¹³. A 2024 review of cosmetic ingredients for sun-damaged skin called the evidence for peptides “the strongest” of those it covered¹⁴.

Can peptides in creams get into the skin?

The skin’s outer layer, the stratum corneum, is its main barrier¹⁵. A 2000 paper argued that a compound’s molecular weight must be under 500 daltons to pass it¹⁵. A 2026 review led by Procter & Gamble scientists says cosmetic peptides have historically been under 500 daltons, about five amino acids⁹.

PubChem gives molecular weights of 802.1 for palmitoyl pentapeptide-4, 578.8 for palmitoyl tripeptide-1 and 694.9 for palmitoyl tetrapeptide-7²¹¹¹². GHK-Cu, the copper complex, is lighter at 401.91⁴⁷. Attaching palmitic acid makes a peptide more fat-soluble, which is meant to help it cross the outer layer⁹¹⁶.

Three studies measured how far these peptides get¹⁰¹⁶¹⁷.

• In hairless-mouse skin in the lab, plain KTTKS was found in no skin layer, while pal-KTTKS reached all of them¹⁶. It measured 4.2 µg/cm² in the outer layer, 2.8 µg/cm² in the epidermis below it and 0.3 µg/cm² in the deeper dermis¹⁶. Neither form passed all the way through the skin sample¹⁶. Both broke down quickly in skin extracts, though pal-KTTKS lasted longer¹⁶.
• In three women, a 2026 study found both Matrixyl 3000 peptides throughout the outer layer after 0.5, 2 and 5 hours, fading with depth¹⁰. The pattern suggested the peptides sat between cells rather than inside them¹⁰. Two authors worked for No7 Beauty Company, part of The Boots Group¹⁰.
• FDA scientists tested Argireline’s peptide because of concern that anti-wrinkle peptides might reach deep skin layers¹⁷. After 24 hours on human cadaver skin, most of it was washed from the surface¹⁷. Of the dose applied, 0.22% was in the outer layer and 0.01% in the epidermis¹⁷. None was detected in the dermis or the fluid beneath¹⁷.

A 2025 review says whether Argireline’s peptide reaches the junctions between nerves and muscles “remains uncertain”⁸.

What does Matrixyl do to your skin?

Pal-KTTKS, the peptide in Matrixyl, was designed to stimulate collagen production and so reduce wrinkles¹². Most trials below were split-face: each person used one product on each half of the face¹¹⁸.

• In a 12-week split-face trial published in 2005, 93 white women aged 35 to 55 used a moisturizer with or without 3 ppm pal-KTTKS¹. The peptide side improved more on image analysis and expert grading, and the women also reported improvement in fine lines¹. The abstract does not say how large the difference was, and the lead author worked at Procter & Gamble¹.
• Two 4-week split-face trials, in 42 and 35 women aged 30 to 70, tested four products combining niacinamide, two palmitoyl peptides and carnosine¹⁸. Compared with no treatment, skin around the eyes was smoother and larger wrinkles looked shallower after 4 weeks¹⁸. Because each product mixed several actives, the trials cannot show what the peptides did alone; the lead author worked at Procter & Gamble¹⁸.
• An 8-week trial in 21 Indonesian women aged 26 to 55 compared acetyl hexapeptide-3, palmitoyl pentapeptide-4 and placebo creams for crow’s feet¹⁹. The authors report that the palmitoyl pentapeptide-4 cream did better, but the abstract gives no figures and calls it an initial study¹⁹. All authors were at a university dermatology department in Jakarta, and the PubMed record lists no funder¹⁹.

In a PubMed search on 8 October 2026, we found no placebo-controlled wrinkle trial in which the Matrixyl 3000 peptides were the only active ingredients²⁰. Two studies came closest²¹²².

• A 2015 methods study compared a blend of the two peptides with a placebo, using ultrasound and skin microscopy²¹. The authors report changes on ultrasound and a better-structured skin matrix than with placebo on microscopy²¹. The abstract gives no number of participants, length or wrinkle result, and the lead author and several co-authors worked at Sederma, in France²¹.
• A 2024 study tested an eye cream that combined both peptides with a yeast and rice ferment and N-acetylneuraminic acid²². For 12 weeks, 37 women aged 20 to 55 used it around one eye, with the other side as the comparison²². Outer-eyelid drooping, under-eye wrinkles and crow’s feet improved significantly more than on the untreated side after 8 weeks²². Dermatologists saw no adverse reactions²². The authors note their small sample and the lack of a placebo group²². Mageline Biology Tech supplied the cream, and the lead author and three co-authors worked at a Mageline research center²².

Is Argireline like Botox?

Botox Cosmetic is onabotulinumtoxinA, a prescription injection²³. It blocks the release of acetylcholine, the chemical messenger that makes muscles contract⁷²³. It does this by cutting SNAP-25, a nerve-ending protein needed to release acetylcholine²³.

Its label covers temporary improvement of moderate to severe frown lines between the eyebrows, crow’s feet, forehead lines and neck bands in adults²³. Two placebo-controlled trials tested it on frown lines²³. At day 30, investigators rated the lines none or mild in 80% of 405 treated people and 3% of 132 on placebo²³. The label says the effect on frown lines lasts about 3 to 4 months²³. Its boxed warning says the effects of botulinum toxin products may spread beyond the injection area²³.

Argireline was designed as a non-toxic molecule that mimics the action of botulinum toxins, modeled on one end of SNAP-25³²⁴. In lab tests, it interfered with the SNARE complex, the protein machinery that lets nerve endings release their messengers³²⁴. The 2002 paper describing it reported “potency similar to that of BoNT A,” meaning botulinum toxin A, but “much lower efficacy than the neurotoxin”²⁴.

In that paper, a cream with 10% of the peptide reduced wrinkle depth by up to 30% in 30 days in healthy women²⁴. The abstract gives no number of volunteers; a 2024 review says ten took part¹⁴²⁴. The lead author was at a university in Alicante, Spain, and the PubMed record lists no funder²⁴.

Later trials of Argireline’s peptide are small and disagree³⁴²⁵.

• In a 2013 trial, 60 Chinese participants were randomly given Argireline or placebo in a 3:1 ratio, around the eyes for 4 weeks³. On a subjective rating, “total anti-wrinkle efficacy” was 48.9% with Argireline and 0% with placebo³. Silicone casts of the skin showed less roughness with Argireline but not with placebo³.
• A second 2013 paper by the same authors reports 60 people, a 3:1 ratio and 48.9% again, so it may be the same trial³²⁶. Neither PubMed record lists a funder³²⁶.
• A 2017 trial from Athens randomized 24 healthy volunteers to two peptides, alone or together, or neither, for 60 days²⁵. One skin-surface measure differed between acetyl hexapeptide-3 and no peptide at day 20, but the abstract lists no such difference at day 60²⁵. The authors concluded that their results “confirm the antiwrinkle activity of acetyl hexapeptide-3”²⁵. Its PubMed record lists no funder²⁵.
• In a 2023 split-face trial, 19 women used a hyaluronic acid serum with or without Argireline on each side for 4 weeks⁴. Camera-based wrinkle scores did not differ significantly between sides, and the author concluded the effect of Argireline “was not proven”⁴. Participants could keep using their own cosmetics⁴. The serum came from CNC cosmetic, a German company, and the author declared no competing interests⁴.
• A 2026 study run and funded by L’Oréal tested a serum combining Argireline’s peptide with dipeptide diaminobutyroyl benzylamide diacetate, gluconolactone, niacinamide and laminaria extract²⁷. In 50 Chinese women with static wrinkles, mean scores improved by 35% to 69% from the start after 12 weeks²⁷. There was no control group, which the authors say may not account for participants’ usual skincare²⁷.
• A 2013 pilot trial at the US National Institutes of Health (NIH) tested the peptide in 24 people with blepharospasm²⁸. The main treatment for blepharospasm, abnormal spasm of the eyelids, is botulinum toxin injections²³²⁸. With the peptide, symptoms took longer to return after toxin injections, 3.7 versus 3.0 months, but this was only a trend²⁸. NIH’s in-house research program funded it, and co-authors came from BCN Peptides, a Barcelona company²⁸.

A 2025 review found that none of the skin-application studies it covered confirmed an effect on muscle contractions⁸. The author of the 2023 trial wrote that Argireline “is not deemed to be an alternative treatment to botulinum toxin”⁴.

Which is better, peptides or retinol?

Tretinoin is a retinoid that the body itself makes from vitamin A²⁹. As Renova 0.02% cream, it is a prescription drug approved to lessen fine facial wrinkles alongside skin care and sun avoidance²⁹. Its label says it “DOES NOT ELIMINATE WRINKLES, REPAIR SUN-DAMAGED SKIN, REVERSE PHOTOAGING”²⁹.

Its trials compared it with vehicle, the same cream without tretinoin²⁹. In four 24-week trials in people with lighter skin, 10% of 279 on Renova improved moderately, versus 3% of 280 on vehicle²⁹. No change was seen in 40% on Renova and 58% on vehicle²⁹. Both groups used sunscreen, protective clothing and moisturizers²⁹. In one trial of 107 people with darker skin, 43% on vehicle and 29% on Renova improved minimally or mildly²⁹. The label says this may reflect the small size of that study²⁹.

Almost all users reported local reactions such as peeling, dry skin, burning and stinging, and about 4% stopped because of side effects²⁹.

In PubMed searches on 8 October 2026, we found no trial in people comparing Argireline, Matrixyl or a copper peptide alone with a retinoid³⁰³¹³². Two trials compared other peptide products with a retinoid³³³⁴.

• In a 2010 trial, 196 women used either a cosmetic regimen with niacinamide, peptides and retinyl propionate or prescription 0.02% tretinoin with SPF 30 sunscreen³³. Wrinkles were judged by expert graders, image analysis and the women themselves³³. After 8 weeks, the cosmetic regimen improved wrinkles more than tretinoin and was better tolerated³³. In groups of 25 who continued to 24 weeks, the benefits were comparable³³. The products mixed several actives, and the lead author worked at Procter & Gamble³³.
• A 2025 trial randomly assigned 96 Asian adults aged 30 to 55 to one of three serums for 56 days³⁴. The serums held 0.002% of a new peptide, cyclized hexapeptide-9, 0.002% retinol, or neither³⁴. Of the 96, 91 finished, and the peptide did significantly better than retinol on every outcome except crow’s-feet roughness³⁴. All eight authors were affiliated with Shanghai Chicmax Cosmetic and Shanghai Kans Biotech³⁴.

Sunscreen has its own trial: in Australia, 903 adults under 55 were randomly assigned to daily sunscreen or use at their own discretion³⁵. After 4.5 years, the daily group showed no detectable increase in skin aging, and aging was 24% less than in the other group³⁵. The National Health and Medical Research Council of Australia funded it³⁵.

What is the downside of peptides in skincare?

Two reviews name poor absorption through the skin as a main drawback⁷¹³. The 2017 review adds that prices “can be quite high”¹³.

The Cosmetic Ingredient Review (CIR), an independent nonprofit set up in 1976, assesses the safety of US cosmetic ingredients⁹. Its 2025 assessment found Argireline’s peptide safe in cosmetics at up to 0.005%, with too little data to judge higher amounts⁹³⁶. The 2002 study that described Argireline tested a cream with 10% of the peptide²⁴. The 2026 review lists the CIR’s verdict for palmitoyl pentapeptide-4, palmitoyl tripeptide-1, palmitoyl tetrapeptide-7 and copper tripeptide-1 as safe in present practices⁹. It reports that two studies predicted palmitoyl pentapeptide-4 to be non-sensitizing, meaning unlikely to cause skin allergy, backed by human patch tests⁹.

The 2005 Matrixyl trial reported that the peptide was well tolerated¹. The 2023 Argireline trial and the 2013 blepharospasm trial reported no significant adverse events⁴²⁸. In a GHK-Cu trial, 1 of 40 women stopped after minor reactions on both sides of the face, which went away without treatment⁴⁸. One side had the GHK-Cu serum and the other a Matrixyl 3000 product⁴⁸. Copper is a recognized contact allergen in some people⁴⁹.

In a PubMed search on 8 October 2026, we found no published case report of an allergic skin reaction to these peptides³⁷. In another, we found no study of them in pregnancy or breastfeeding³⁸. By contrast, the Renova label says tretinoin cream “should not be used during pregnancy”²⁹.

A 2021 case report describes a patient who developed redness, lumps and abscesses a week after argireline injections in the forehead and temples³⁹. Doctors found Mycobacterium abscessus, a bacterium, and the lesions faded over 5 months of antibiotics³⁹. The authors called it the first reported case of this infection after argireline injection³⁹. Injected peptides are outside this guide; see our skin ranking.

Is a peptide cream a cosmetic or a drug?

Under US law, a product’s intended use decides whether it is a cosmetic, a drug or both⁴⁰. FDA judges intended use from claims on labels, in advertising, on the internet and in other promotion⁴⁰. A claim to “regenerate cells” is one of its examples of a drug claim⁴⁰. FDA also says the term “cosmeceutical” has no meaning under the law⁴⁰.

A product that makes lines less noticeable just by moisturizing is a cosmetic⁵. One meant to remove wrinkles or increase the skin’s collagen production is a drug or a medical device⁵. Drugs need FDA approval for safety and effectiveness, but cosmetics, apart from color additives, need no FDA approval before sale⁵⁴⁰. FDA says it is concerned about anti-wrinkle and anti-aging claims on cosmetics that involve supposed effects on the skin’s structure or function⁵.

By our reading, a peptide cream sold with cosmetic claims therefore needs no proof that it works⁵⁴⁰. The 2017 review lists the absence of premarket rules among the advantages of cosmetic peptides¹³.

FDA warning letters show the intended-use test at work⁴¹⁴².

• In July 2024, FDA told a skincare seller that its acid peels were unapproved new drugs⁴¹. Website claims it cited included “Reduce fine lines and wrinkles” and “Stimulate collagen production”⁴¹. The products were peels, not peptides⁴¹.
• In April 2026, FDA told a sunscreen maker that claims such as “Promotes collagen production” showed its featured ingredients were meant as “active ingredients”⁴². It added that one label featured collagen peptides out of proportion to their role in the formula, which further misbranded the products⁴².

For “research use only” vials, US drug law looks at what the seller’s marketing shows a product is for, not only its label disclaimer⁵⁰. Our 2026 gray-market briefing covers those sellers.

Acetyl hexapeptide-3, an older name for Argireline’s peptide, was nominated for FDA’s 503B list of bulk substances for drug compounding⁴³. As of 8 October 2026, the list, updated 21 March 2025, puts it in Category 3: nominated without enough information for FDA to evaluate⁴³⁴⁴. FDA says it would consider action against a 503B compounder that uses a Category 3 substance⁴⁴.

What do copper peptides do for skin?

On ingredient lists, GHK-Cu appears as copper tripeptide-1⁴⁷. Our GHK-Cu page covers it in depth.

• A 2026 systematic review of GHK-Cu used alone for cosmetic purposes included 20 studies: 18 preclinical and 2 randomized trials⁵¹.
• In 20 women over 8 weeks, wrinkle volume fell by an average 24.1% on the GHK-Cu side versus 15.0% on the vehicle side⁴⁸. The serum’s maker funded the study⁴⁸.
• After CO2 laser resurfacing, 13 patients saw no objective benefit from GHK-Cu skin care, though they rated their skin quality higher⁵².
• GHK-Cu is not approved as a drug and is sold as a cosmetic ingredient⁵³⁵⁴. It is also sold as vials that many buyers inject, but we found no published study that injected it on its own in people⁵³⁵⁵.

The evidence at a glance

A tier grades the best human evidence for any use, not whether a compound is safe. Whether each one works for the use people take it for, and its legal status: the evidence table. How we grade: our method.

Questions people ask

Go deeper

• Collagen peptides: what the trials show, and who paid for them
• Compounded semaglutide, tirzepatide and microdosing: what the evidence says
• GLP-1s and peptides before surgery, at home or in Seoul
• Peptide blends, checked against the evidence
• Peptide injection sites: what the approved labels say
• Peptide side effects: what trials, labels and safety alerts show
• Peptide therapy, graded on the evidence
• Peptides for hair: what the trials show, and how they compare with minoxidil
• Peptides for women: what the labels and trials say
• What are peptides? The science in plain English
• Every peptide, graded: the evidence table
• Best peptides for weight loss, ranked
• Best peptides for healing, ranked
• Best peptides for skin and tanning, ranked
• Best peptides for growth hormone, ranked
• Best peptides for libido, ranked
• Best peptides for longevity, ranked
• Best peptides for focus and sleep, ranked
• Best peptides for immune support, ranked
• Are peptides legal? The legal tracker
• Peptides compared, head to head
• The 2026 gray-market briefing

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