Eyelash serums: myristoyl pentapeptide-17 vs bimatoprost

The one approved lash drug

Bimatoprost started as a glaucoma eye drop. Patients noticed their eyelashes growing, and in 2008 a 0.03% solution was approved for lashes as Latisse. Its current US label indicates it to treat hypotrichosis of the eyelashes, meaning inadequate lashes, by increasing their growth, including length, thickness and darkness. It is applied once nightly with a sterile single-use applicator along the base of the upper lashes, not dropped into the eye ¹.

The evidence is strong by cosmetic standards. In a five-month randomised trial of 278 people, 78.1% on bimatoprost against 18.4% on the vehicle improved by at least one grade on a global eyelash scale at 16 weeks, with significantly greater gains in length, thickness and darkness measured by image analysis; conjunctival redness was the only adverse event significantly more common than with vehicle (randomised trial) ². A pooled analysis of six randomised, double-masked trials from 2007 to 2012 found overall adverse event rates similar to vehicle in people with ordinary lash thinning, with eye redness, eyelid itching, eyelid darkening and other mostly early effects (pooled trial data) ³. It did not work everywhere: in alopecia areata, a 2009 study found no lash growth (human study) ⁴.

How a prostaglandin grows lashes

Lashes, like scalp hair, cycle through a growth phase, a short transition and a resting phase before they fall out. The Latisse label says the precise mechanism is unknown but that lash growth is believed to come from increasing the proportion of hairs in the growth phase and how long that phase lasts ¹. That explains why results take weeks to appear and fade after stopping: the drug extends a natural cycle rather than creating new follicles. The label's pharmacokinetic data, from the glaucoma version dropped into the eye, show blood levels peaking within ten minutes and falling below detection in most people within 90 minutes ¹.

Lash loss after chemotherapy and in children

Bimatoprost has also been tested where lash loss has a medical cause. In a one-year trial of 130 people whose lashes thinned after chemotherapy, more responded on bimatoprost than on the vehicle at four months (37.5% against 18.2%) and six months (46.9% against 18.2%), and responder rates reached about 62% to 68% by twelve months when everyone used the drug; eye redness and punctate keratitis were the most common adverse events (randomised trial) ⁵. In a 71-person trial in children and adolescents, lash prominence improved in 70.8% on bimatoprost against 26.1% on the vehicle, but the benefit was significant in healthy adolescents, not in the subgroups after chemotherapy or with alopecia areata (randomised trial) ⁶. The label summarises that paediatric study and reports no new safety issues ¹. No peptide serum has been tested in either group. For someone whose lashes fell out during cancer treatment, that makes the approved drug the only option with trial data behind it, and the conversation belongs with the oncology or eye team, who can weigh it against eye sensitivity during and after treatment.

What the Latisse label warns about

The label is explicit. Used by people who also take prostaglandin eye drops for high eye pressure, it may reduce their pressure-lowering effect, so they need monitoring. Pigmentation of the eyelids and iris may occur, and iris pigmentation is likely to be permanent. The label also lists hair growth outside the treatment area, intraocular inflammation and macular oedema among the reactions described in its warnings, and gives eye itching, conjunctival redness and skin darkening as the most common reactions, in roughly 3% to 4% of users ¹.

Those warnings matter for the rest of this article, because the same family of drugs turns up, unlabelled, in some products sold as cosmetics.

Peptide lash serums: what the evidence shows

Peptide lash serums are cosmetics, sold without a prescription and marketed as a gentler alternative. The ingredient most often named is myristoyl pentapeptide-17, a short peptide with a fatty acid attached to help it penetrate, usually combined with biotin-linked peptides such as biotinoyl tripeptide-1 and with conditioning ingredients.

The evidence for myristoyl pentapeptide-17 itself is, as far as the medical literature goes, absent. We searched PubMed on October 3, 2026 for the phrase 'myristoyl pentapeptide' in titles and abstracts, and for 'myristoyl' with 'eyelash': both searches returned no records ⁷. Claims of lash growth come from ingredient suppliers and brands, not from peer-reviewed trials. Evidence grade: none in the peer-reviewed literature.

The closest published study tested a serum combining peptides and glycosaminoglycans in 30 women for 12 weeks, without a control group. Lash length improved on software measurements and satisfaction rose to 84%, with no adverse effects reported (open-label trial, no control) ⁸. Without a placebo or vehicle group, it cannot separate the serum's effect from conditioning, better imaging or expectation, and it does not say which peptides did what.

Prostaglandins hidden in 'peptide' serums

Here is the catch. Some lash serums sold as cosmetics contain prostaglandin analogues, chemical relatives of bimatoprost, listed under less familiar names: a 2022 study of these products named bimatoprost, norbimatoprost, isopropyl cloprostenate, dechloro-dihydroxy-difluoro-ethylcloprostenolamide and methylamido-dihydro-noralfaprostal among the ingredients it found (human case report and photo study) ⁹. These products can work, because prostaglandins grow lashes, but they also bring prostaglandin side effects without a prescription, a medical label or a warning about eye pressure or pigmentation.

The same 2022 study described a 35-year-old woman who developed thin, darker skin and hollowing around the eyes after ten months of a cosmetic serum containing isopropyl cloprostenate, which reversed six months after stopping. Blinded graders also scored manufacturers' own before-and-after photographs: users of prostaglandin-containing lash serums showed significantly more signs of the fat and volume loss around the eyes known from prostaglandin glaucoma drops than users of non-prostaglandin serums or false lashes (case report and graded photographs) ⁹.

Regulators have started testing. A 2025 study from South Korea's Ministry of Food and Drug Safety developed a method to detect 11 prostaglandin analogues in cosmetics and, applying it to lash serums on the market, found norbimatoprost in one product (laboratory analysis) ¹⁰. A serum marketed for its peptides may contain a prostaglandin too; reading the full ingredient list matters.

How to read lash serum claims

Lash serum marketing leans on three kinds of evidence, and each has a weakness. Before-and-after photographs are chosen by the seller, and lighting, angle, mascara residue and curling change how lashes look; the 2022 study used manufacturers' own photos precisely because they are what consumers see, and still found signs of side effects in them ⁹. Satisfaction percentages, like the 84% in the open peptide-serum trial, measure how people feel about their lashes, not how much they grew ⁸. And 'clinically tested' often means an open study with no comparison group. The bimatoprost trials show what a fair test looks like: a vehicle group, masked assessors, a validated grading scale and image measurements, and even then nearly one in five people on the vehicle improved by a grade ². A lash peptide claim without a vehicle-controlled trial cannot tell you how much of the change was the peptide.

If you want longer lashes

The evidence points in an awkward direction. The product that clearly works, bimatoprost, is a prescription drug with real but generally manageable side effects that a doctor can discuss and monitor, particularly for anyone with glaucoma or on eye-pressure drops. The products marketed as gentle peptide alternatives either have no published evidence or, in some cases, contain unlabelled prostaglandin cousins of the drug, with the side effects and none of the oversight.

A serum that genuinely contains only peptides and conditioners is unlikely to cause prostaglandin effects; it is also unlikely to have been shown to grow lashes. A serum that dramatically lengthens lashes in weeks is worth checking for prostaglandin analogues on the ingredient list, especially names ending in -prost, -prostenol or -prostenate, or containing 'cloprostenate'.

Regulatory status, as of October 3, 2026

Bimatoprost 0.03% is FDA-approved, as Latisse, for eyelash hypotrichosis; the current label is version 25 on DailyMed ¹. Peptide lash serums are sold as cosmetics, without the clinical testing and labelling an approved drug carries. Cosmetic peptides such as myristoyl pentapeptide-17 are not drugs in our encyclopedia's sense and are not on WADA's list. Our related pages on argireline and copper peptides for skin look at the evidence for other cosmetic peptides.

Questions to ask before using a lash serum

• Does the ingredient list include bimatoprost, norbimatoprost, isopropyl cloprostenate or another '-prost' ingredient?
• Do I have glaucoma or high eye pressure, or use prostaglandin eye drops? If so, an eye doctor should know before I use any lash product with a prostaglandin.
• Do I have light-coloured eyes? Iris darkening from prostaglandins is likely to be permanent.
• What evidence supports the peptide in this serum: a published controlled trial, or the supplier's own data?
• If I notice hollowing, darker skin or redness around the eyes, should I stop and see a doctor? Yes.

The bottom line

The only lash product with strong evidence is a prescription prostaglandin drug, bimatoprost, whose label spells out its risks. The peptides that lash serums advertise, led by myristoyl pentapeptide-17, have no peer-reviewed trials. And some products sold as peptide serums contain unlabelled prostaglandin relatives that can cause fat loss around the eyes. Check the ingredient list, and if you want the version that is known to work, ask a doctor about the approved one.

Frequently asked questions

Do peptide lash serums work?

There is no peer-reviewed trial of myristoyl pentapeptide-17, the most common lash peptide. One uncontrolled study of a peptide and glycosaminoglycan serum in 30 women reported longer lashes at 12 weeks.

What is the difference between a peptide lash serum and Latisse?

Latisse is bimatoprost 0.03%, an FDA-approved prostaglandin drug with randomised-trial evidence and labelled side effects. Peptide serums are cosmetics with little or no published evidence.

Can lash serums cause eye problems?

Serums containing prostaglandin analogues can cause redness, itching, skin darkening, iris pigmentation and loss of fat around the eyes. Some cosmetic serums contain these ingredients under less familiar names.

How do I know if my lash serum contains a prostaglandin?

Check the ingredient list for bimatoprost, norbimatoprost, isopropyl cloprostenate or other names ending in -prost or containing cloprostenate.

Is myristoyl pentapeptide-17 safe?

Its safety and effectiveness have not been tested in any peer-reviewed clinical trial in PubMed as of October 3, 2026.

Related on Grey Peptides

• Biotinoyl tripeptide-1
• Copper peptides for skin
• Argireline

Sources

1. Allergan. LATISSE (bimatoprost ophthalmic solution) 0.03% prescribing information: Indications and Usage, Dosage and Administration, Warnings and Precautions, Adverse Reactions. DailyMed set 34f83d9d-2c64-463e-8a90-9a460fedfead, version 25, published December 23, 2025; read October 3, 2026.
2. Smith, S., et al. (2012). Eyelash growth in subjects treated with bimatoprost: a multicenter, randomized, double-masked, vehicle-controlled, parallel-group study. J Am Acad Dermatol, 66(5), 801-6. PMID: 21899919
3. Wirta, D., et al. (2015). Bimatoprost 0.03% for the Treatment of Eyelash Hypotrichosis: A Pooled Safety Analysis of Six Randomized, Double-masked Clinical Trials. J Clin Aesthet Dermatol, 8(7), 17-29. PMID: 26203317
4. Roseborough, I., et al. (2009). Lack of efficacy of topical latanoprost and bimatoprost ophthalmic solutions in promoting eyelash growth in patients with alopecia areata. J Am Acad Dermatol, 60(4), 705-6. PMID: 19293023
5. Wirta, D., et al. (2015). Safety and Efficacy of Bimatoprost for Eyelash Growth in Postchemotherapy Subjects. J Clin Aesthet Dermatol, 8(4), 11-20. PMID: 26060513
6. Borchert, M., et al. (2016). An evaluation of the safety and efficacy of bimatoprost for eyelash growth in pediatric subjects. Clin Ophthalmol, 10, 419-29. PMID: 27022239
7. Grey Peptides search of PubMed, October 3, 2026: the phrase 'myristoyl pentapeptide' in titles and abstracts, and 'myristoyl' in titles with 'eyelash' in titles or abstracts, each returned 0 records.
8. Fernandez-Gonzalez, P., et al. (2024). Open clinical trial evaluating the efficacy of a novel eyelash growth enhancer with peptides and glycosaminoglycans. J Cosmet Dermatol, 23(6), 2170-2180. PMID: 38572527
9. Jamison, A., et al. (2022). Do Prostaglandin Analogue Lash Lengtheners Cause Eyelid Fat and Volume Loss? Aesthet Surg J, 42(11), 1241-1249. PMID: 35700523
10. Han, K. M., et al. (2025). HPLC method for detecting prostaglandin F(2α) analogs in cosmetics: Optimization for chromatographic separation and sample preparation. J Pharm Biomed Anal, 260, 116788. PMID: 40056490

Educational information, not medical advice. Each dose in this guide names its source, an approved label or a published study. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose.