Is palmitoyl pentapeptide-4 FDA-approved, and what does the research show?

What is palmitoyl pentapeptide-4?

Palmitoyl pentapeptide-4 is a synthetic peptide made for skin care products ². A peptide is a short chain of amino acids, the units proteins are built from. This one has five: lysine, threonine, threonine, lysine and serine, written KTTKS ¹,². The sequence is a piece of type I procollagen, the precursor the body trims to make collagen, the main structural protein of skin ¹. One end carries palmitic acid, a fatty acid 16 carbons long, which helps the peptide mix with oils and pass into skin ².

The industry's ingredient dictionary lists its function as skin conditioning ². The Cosmetic Ingredient Review, the expert safety panel the cosmetics industry's trade association funds, records it under the trade name Matrixyl, a mixture containing 0.01 percent of the peptide ²,⁷. The Review says it, its panel and the review process "are independent from the Council and the cosmetics industry," the Council being that trade association ⁷.

A 2012 summary from the peptide's maker, Sederma, says it was previously named palmitoyl pentapeptide-3 ². Researchers write it as pal-KTTKS ⁵. The name also covers a close variant, KTSKS ².

Is palmitoyl pentapeptide-4 FDA-approved?

No. Palmitoyl pentapeptide-4 is not FDA-approved as a drug: Drugs@FDA, FDA's database of approved drugs, lists no approved palmitoyl pentapeptide-4, pal-KTTKS or Matrixyl product as of November 9, 2026 ⁴. It is sold as a cosmetic ingredient, a class FDA does not approve in advance, color additives apart ³. FDA puts it this way on its cosmetics authority page, current as of November 18, 2025: "the law does not require cosmetic products and ingredients, other than color additives, to have FDA approval before they go on the market" ³. Safety is the seller's duty: firms that make or market a cosmetic "have a legal responsibility to ensure the safety of their products," and neither the law nor FDA's rules prescribe particular tests ³.

The line between a cosmetic and a drug is drawn by what the product is meant to do ⁸. FDA judges that intent from the claims on the label and in advertising and from what buyers expect of the product ⁸. It also weighs any ingredient with a well-known therapeutic use, such as fluoride in toothpaste ⁸.

For wrinkle products FDA has spelled this out, on a page current as of February 25, 2022 ⁹. Moisturizing is a cosmetic claim, so a product sold "to make lines and wrinkles less noticeable, simply by moisturizing the skin" stays a cosmetic ⁹. A product sold "to remove wrinkles or increase the skin's production of collagen" crosses into "a drug or a medical device" ⁹.

The same page records FDA's concern "about drug claims made for products marketed as cosmetics, such as skin care products with anti-wrinkle or anti-aging claims that involve supposed effects on the structure or function of the skin" ⁹. That matters here because the 2005 trial's authors describe pal-KTTKS as "designed as a topical agent to stimulate collagen production" ⁵. "Cosmeceutical," the word sellers use for such products, has no standing in the law ⁸.

The Modernization of Cosmetics Regulation Act of 2022 gave FDA new powers over cosmetics already on the market ¹⁰. It can now order a recall of a cosmetic likely to cause serious harm or death "if the responsible person," the company named on the label, "refuses to do so voluntarily" ¹⁰. That company must also tell FDA about any serious adverse event within 15 business days ¹⁰. None of this adds a review before sale: a cream with palmitoyl pentapeptide-4 in it reaches the shelf with FDA having checked neither its safety nor its effectiveness ³,⁹.

See the FDA status of every peptide, updated weekly.

How does palmitoyl pentapeptide-4 work?

The proposed mechanism is a collagen signal. Shown in cells: in 1993, researchers tested pieces of type I procollagen on fibroblasts ¹. KTTKS, five residues long, was the shortest piece that still drove them to make type I and type III collagen and fibronectin ¹,¹¹. Fibroblasts are the skin cells that build its supporting matrix. The palmitic acid tail is there to carry the peptide through the skin's outer layer, which the bare peptide crosses poorly ².

Whether enough reaches living skin is unsettled. In a laboratory study on hairless mouse skin, about 15 percent of the applied peptide stayed in the skin, 0.6 percent of it in the dermis ². None in a measurable amount passed through ². A 2011 review found "a sound in vitro basis," meaning laboratory evidence, for its action on fibroblasts, but "a surprising absence of in vitro skin penetration data" and "relatively few clinical studies" ¹¹.

What does the research show?

Studied in people: 93 Caucasian women aged 35 to 55 took part in a 12-week, double-blind, placebo-controlled, randomized split-face study ⁵. Each used a moisturizer on one side of the face and the same moisturizer with 3 parts per million of pal-KTTKS on the other ⁵. The treated side showed a significant reduction in wrinkles and fine lines against the control side, by image analysis and by expert graders, and the women reported the same ⁵. The first author worked at Procter & Gamble, which makes skin care products ⁵.

Studied in people: an eight-week, double-blind, randomized trial in Indonesia divided 21 women aged 26 to 55 among three creams ⁶. The creams held palmitoyl pentapeptide-4, acetyl hexapeptide-3 or a placebo, applied twice daily around the eyes ⁶. Acetyl hexapeptide-3 is the older name of acetyl hexapeptide-8, by the Cosmetic Ingredient Review panel's 2020 tentative report ¹². The authors report that the pentapeptide cream "demonstrated better results" than the other two, and call the work an initial study that needs more people and more time ⁶.

The one larger trial tested a blend, not the ingredient alone. An eight-week randomized trial in 196 women compared a three-product cosmetic regimen containing niacinamide, peptides and retinyl propionate with prescription 0.02 percent tretinoin ¹³. The regimen improved wrinkle appearance more than tretinoin at eight weeks, about equally at 24 weeks in the 48 women who continued that long, and with less irritation ¹³. The Cosmetic Ingredient Review identifies palmitoyl pentapeptide-4 as one of those peptides, so the result belongs to the regimen and not to the peptide ²,¹³. No study opened followed the ingredient alone past 12 weeks, and none measured how much enters human skin ⁵,⁶,¹¹.

What are the side effects?

The documented reactions are mild and local. In the 93-woman trial the peptide "was well tolerated by the skin" ⁵. The Cosmetic Ingredient Review's record describes a 48-hour patch test of a formulation with 0.12 percent of the KTSKS variant, diluted to 15 percent in water ². It caused no irritation in 11 people ².

A repeated-insult patch test applies the product to the same skin again and again to look for allergy. In 106 people, the same diluted formulation caused no irritation or sensitization in that test ².

A Matrixyl mixture with 0.01 percent of the peptide caused "very slight erythema," meaning redness, in 1 of 10 people in an acute irritation test ². The same mixture caused no irritation or sensitization in a 51-person repeated-insult patch test ². In one hen's egg membrane assay, a laboratory stand-in for the eye, the mixture scored as a moderate eye irritant ². A different formulation did not irritate a human corneal cell model, and the peptide at 0.01 percent did not irritate rabbit eyes ².

In a 20-patient randomized trial during breast radiotherapy, a cream blending Matrixyl with two other actives produced mild itching and scattered skin eruptions more often than the comparison lotion ¹⁴. The trial's only adverse events, including one suspected allergic reaction, were in the cream group, and the result belongs to the blend ¹⁴.

In a final report released in November 2024, the panel concluded that palmitoyl pentapeptide-4 is "safe in cosmetics in the present practices of use and concentration described in this safety assessment," with leave-on products reported at up to 0.0012 percent ². It noted "the lack of developmental and reproductive toxicity and carcinogenicity data" ². It judged the low use concentrations, the limited skin absorption, negative tests for genetic damage and a negative test for estrogen-like activity enough to set that aside ². No source opened measured the peptide in the bloodstream, and the one penetration study, in mouse skin, found none in a measurable amount passing through ².

In sport

Palmitoyl pentapeptide-4 is not named on the 2026 Prohibited List of WADA, the World Anti-Doping Agency, under that name, as Matrixyl or as pal-KTTKS ¹⁵.

What JumpstartMD offers

JumpstartMD does not prescribe palmitoyl pentapeptide-4. Our peptide library covers it so you have the facts on its FDA status and the evidence, current as of November 10, 2026.

Ready to talk?

Book FREE Consultation

Share your details and a JumpstartMD team member will reach out shortly. Or call 408.478.3496 for your free, no-obligation consultation.

Share your details and a JumpstartMD team member will reach out when we open.

Disclaimer

Compounded medications are not FDA-approved, and FDA does not review their safety, effectiveness, or quality before they are marketed. A licensed clinician decides after an evaluation whether a peptide is appropriate for you, and not every patient will qualify.