"Peptides for nails" is used for four different things: a collagen drink, a keratin capsule, a peptide serum or cuticle oil, and an antifungal peptide being developed as a drug for nail fungus. They share a word and almost nothing else. This page separates them and counts the human trials behind each, with who paid for them, as of 10 November 2026. It ranks no product and recommends nothing; a nail that is changing colour, thickening or lifting is a question for a doctor, dermatologist or podiatrist.
The four meanings, and the evidence behind each
| What is sold as "peptides for nails" | Human nail trials found | Placebo-controlled? | Who funded or ran them |
|---|---|---|---|
| Oral collagen peptides | 1 nail study + 1 skin trial that also scored nail colour | the nail study no; the skin trial yes | a collagen research institute; the collagen maker |
| Oral keratin (solubilised keratin) | 1 | yes | the keratin maker |
| Topical cosmetic peptides (serums, oils, lacquers) | 0 | — | — |
| Antifungal peptide for nail fungus (NP213) | 2 phase 2a published, 1 phase 2b reported unpublished | yes | the developer and its licensee |
Collagen peptides you swallow
The study most often cited for nails is small and open-label. Twenty-five participants took 2.5 g a day of a specific bioactive collagen peptide (Verisol) for 24 weeks, followed by 4 weeks off (Hexsel et al., Journal of Cosmetic Dermatology 2017):
| Measure | Result reported |
|---|---|
| Nail growth rate | +12% |
| Frequency of broken nails | −42% |
| Global clinical improvement | 64% of participants |
| Improvement 4 weeks after stopping | 88% |
There was no placebo group, so none of these figures can be separated from time, season or simply paying attention to nails. Two of the six authors are listed at the Collagen Research Institute in Kiel, Germany; the abstract does not state who funded the study. The study's own result is as far as it goes.
The one placebo-controlled trial found that measured nails at all was a skin trial. Eighty-five women aged 43 to 65 took 5 g of collagen peptides or maltodextrin daily for 84 days; nail colour was one of several secondary measures, and the abstract reports it improved sooner in the collagen group, by day 28, while the placebo group reached similar effects by day 84 (Vleminckx et al., Journal of Cosmetic Dermatology 2024). The authors are from the collagen maker, Rousselot, and from a contract laboratory. Nail growth and breakage were not measured.
Collagen supplements, their skin trials and their funders are set out in full on our collagen peptides for hair and skin page; this page does not repeat them.
Keratin you swallow
Keratin is the protein nails are made of, and one supplement trial targets it. Fifty women were randomised to two capsules a day of Cynatine HNS — 500 mg of a solubilised keratin plus vitamins and minerals — or maltodextrin for 90 days, with a dermatologist scoring nail appearance and breakage (Beer et al., ScientificWorldJournal 2014). The paper reports statistically significant improvements in nail strength and appearance against placebo. Three things limit it:
- The capsule is not keratin alone. It contains vitamins and minerals as well, so the trial cannot say whether the keratin did anything.
- The maker paid for it. The full text states that Roxlor Global funded the study and supplied the capsules, that one author is Roxlor's general manager, and that the other two receive consulting fees from the company.
- It is one trial of 50 people. No independent replication was found.
A 2025 review of nail supplements lists collagen peptides and solubilised keratin, along with biotin, MSM and orthosilicic acid, as having "been shown to improve the clinical appearance of nails", and in the same summary notes that "manufacturers are not required to carry out efficacy and safety studies before marketing" (Zaraa and Richert, Skin Appendage Disorders 2025).
Peptides you put on the nail: the trial that has not been run
Nail serums, cuticle oils and strengthening lacquers increasingly list peptides — palmitoyl peptides, biotinoyl tripeptide-1, copper peptides, hydrolysed keratin. A PubMed search on 10 November 2026 for nails together with those ingredients and topical, lacquer, serum, cuticle, polish or cosmetic terms returned one record: a laboratory study of feather keratin on hair fibre, not nails (BMC Biotechnology 2013). No trial of a topical peptide nail product was found.
The absence is not because nail products cannot be tested. A search for brittle nails with topical or lacquer terms returned 19 records on the same day, including randomized trials of non-peptide products. In one, 50 people with brittle nails used a hydroxypropyl chitosan lacquer, alone or with 10 mg of oral biotin daily, for four months; the nail-damage score fell by 57% and 62%, with an assessor who did not know the group (Chiavetta et al., Dermatologic Therapy 2019). There was no untreated group, and one author works for the lacquer's maker, but it shows the design is possible. The peptide versions simply have not been put through it.
The same gap — a peptide claim on the label and no trial of the product type — appears in our peptide body lotion census. Getting any ingredient through the nail plate is its own problem: the antifungal peptide below was designed specifically to cross it, which is the property a cosmetic peptide has never been shown to have.
Antifungal peptides: a drug candidate, not a cosmetic
The most rigorous peptide research on nails is about something else entirely: nail fungus (onychomycosis), which causes much of the thickening, yellowing and crumbling people try to fix cosmetically.
NP213 (Novexatin) is a synthetic peptide modelled on the body's own antimicrobial peptides, made to pass through the nail plate. Its developer's 2020 paper reports the human studies (Mercer et al., Medical Mycology 2020):
| Study | People | Applied | Result reported |
|---|---|---|---|
| Phase 1/2a (EudraCT 2008-001496-29) | 12 + 48, vs vehicle | daily for 28 days | 23.1% of mild-to-moderate cases culture- and microscopy-negative at day 180; 43.3% culture-negative |
| Phase 2a (NCT02343627) | 47, vs vehicle | daily for 28 days | 56.5% culture-negative at day 360 among the 23 NP213 patients who finished, 0 of 9 on vehicle |
| Phase 2b (NCT02933879) | 184 | 56 days, one or two courses | 27% and 36% culture-negative at day 365 — reported as "manuscript in preparation" |
Three things are worth knowing that the drug's coverage rarely says:
- On the trial registry it has another name. A ClinicalTrials.gov search for "NP213" or "Novexatin" on 10 November 2026 returned nothing; the studies are listed as "NVXT Solution", sponsored by Sun Pharmaceutical Industries — 47 people completed in January 2016, and 184 people completed in June 2018. No phase 3 record was found under either name.
- Culture-negative is not cured. A negative culture means no fungus grew from the sample. The stricter measure, negative on both culture and microscopy, was 23.1% in the first study, and the paper does not report a complete clinical cure rate for the phase 2b.
- Every author is or was employed by, or directs, the developer, NovaBiotics.
A second candidate, a plant defensin called Ppdef1, killed nail fungi and penetrated human nail in laboratory work; its authors are shareholders in the company that owns it and hold its patents, and no human trial was reported (van der Weerden et al., Journal of Fungi 2023). The topical drugs added to treatment in the last decade, named in a 2022 review — efinaconazole, tavaborole and luliconazole — are not peptides (Gregoriou et al., Journal of Fungi 2022).
None of this applies to a cosmetic peptide serum. An antifungal drug candidate tested in toenail infection says nothing about a palmitoyl peptide in a cuticle oil, and a beauty product that borrowed the antifungal results would be claiming evidence it does not have.
What is not established
- Whether any topical cosmetic peptide changes nail strength, growth or appearance: no trial found.
- Whether oral collagen peptides improve brittle nails against placebo: not tested in a nail-focused trial.
- Whether the keratin in a keratin-plus-vitamin capsule is what changed nails: the trial cannot separate it.
- Whether NP213 will become an approved treatment: no phase 3 found; the phase 2b is unpublished.
The hair version of the same question — peptides against minoxidil and finasteride — is on our peptides for hair growth hub, and the skin trials are counted on peptides for skin.