GHK-Cu vs LL-37
A copper-based ingredient sold in skin creams and injections for wrinkles, hair loss and healing. It speeds wound healing in rats, but no proper human trial exists. 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.
Both sit at grade C: animal and cell studies. Neither is FDA approved.
Evidence
CAnimal and cell studies
CAnimal and cell studies
Human studies cited
Animal or cell studies cited
Why the grade
For skin repair and wound healing, the use GHK-Cu is best known for, the primary studies in hand are cell cultures and rat and mouse experiments, including a hair-growth study in fuzzy rats. The human cosmetic results that reviews describe come from manufacturer-run tests that are summarised and not published in full, so no controlled human trial with a known sample size can be named.
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.
FDA
Not approved
GHK-Cu is not approved by the FDA for any use. As copper tripeptide-1 it is sold in cosmetics, which sit outside FDA drug approval. The FDA placed the injectable form in Category 2 of its compounding list in 2023 over safety risks, and the agency now lists that nomination as withdrawn; it plans to bring GHK-Cu before its Pharmacy Compounding Advisory Committee by the end of February 2027.
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for the FDA's compounding bulk-substances list and placed in Category 2 (significant safety risk); the nomination was withdrawn, the FDA removed it from the category in April 2026, and a Pharmacy Compounding Advisory Committee review is planned before the end of February 2027.
Sold for
GHK-Cu is sold as an anti-aging and wound-healing peptide, in serums for wrinkles and hair thinning and as an injectable for recovery.
LL-37 is sold as an injectable 'natural antibiotic' that fights infections, breaks up biofilms, heals wounds, and modulates immunity.
Studies say
Cell and animal work shows that GHK-Cu raises collagen production and speeds wound closure in rats, but the human evidence is limited to cosmetic tests reported inside reviews, which is why the grade is C.
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.
Class
Copper-binding tripeptide
Host-defense antimicrobial peptide
Route
Several routes
Injection