LL-37 vs Copper tripeptide-1
It is sold as an injected natural antibiotic and healer. The only trials used it on skin sores and gave mixed results, and injecting it has never been studied in people. A skin-care ingredient sold to firm skin, soften wrinkles and regrow hair. The one controlled human trial, of 13 patients, found no skin benefit.
Both sit at grade C: animal and cell studies. LL-37: Not approved. Copper tripeptide-1: Cosmetic ingredient.
Evidence
CAnimal and cell studies
CAnimal and cell studies
Human studies cited
Animal or cell studies cited
Why the grade
Two randomized placebo-controlled trials exist, both of LL-37 applied topically to chronic wounds: 148 patients with venous leg ulcers (negative on the primary endpoint) and a smaller diabetic foot ulcer trial. The injected 'immune support' use sold online has no human data at all. The rest of the human literature is observational work on the body's own LL-37 in wounds, psoriasis, and rosacea, plus cell and mouse mechanism studies. For the use it is sold for, that is C.
For the skin anti-ageing use, the controlled human evidence is a single randomized trial of 13 patients after CO2 laser resurfacing, which found no objective difference in redness or wrinkles. The rest is gene-expression work in cultured cells, animal wound and lung-injury models, and cosmetic-company studies summarized in reviews written by the peptide's discoverer.
FDA
Not approved
Not approved by the FDA for any use and sold as a research chemical. LL-37 was nominated for the FDA's compounding bulk-substances list and placed in Category 2 (significant safety risk); the nomination was withdrawn, the FDA removed it from the category in April 2026, and a Pharmacy Compounding Advisory Committee review is planned before the end of February 2027.
Cosmetic ingredient
Copper tripeptide-1 is a cosmetic ingredient and sits outside FDA drug approval; no copper tripeptide-1 or GHK-Cu product is approved by the FDA as a drug for any use. Injectable GHK-Cu sold online is not approved and is sold as a research chemical.
Sold for
LL-37 is sold as an injectable 'natural antibiotic' that fights infections, breaks up biofilms, heals wounds, and modulates immunity.
Copper tripeptide-1 is marketed in serums as a collagen-building, wound-healing peptide that firms skin, softens wrinkles and regrows hair.
Studies say
Topical LL-37 has two small wound-healing trials with mixed results, the body's own LL-37 is well studied and drives inflammation in psoriasis and rosacea, and there are no human data on injecting it, so the evidence for the marketed use is grade C.
Cell and animal studies show it switches on repair genes and speeds wound closure, but the one blinded human trial found no measurable skin benefit over the control regimen, so the evidence is C.
Class
Host-defense antimicrobial peptide
Carrier/copper peptide
Route
Injection
Topical