How LL-37 works
A human defense peptide with mixed topical wound-trial results and no established injection regimen.
Also called: LL37, Cathelicidin LL-37, hCAP18/LL-37.
Anti-inflammatory and antimicrobial peptides · Human cathelicidin antimicrobial and immune-signaling peptide.
LL-37 can damage microbial membranes and send signals to immune and skin cells. It can help blood vessels and wound tissue grow in experiments. It can also trigger inflammation, including immune responses to the body's own DNA. Its effects depend on the tissue and concentration.
- Microbial membranes: Disrupts membranes in laboratory studies.
- FPR2 / FPRL1: Signals to immune and vessel-lining cells; promoted new blood vessels in animals.
- Self-DNA and TLR9: Helps self-DNA trigger interferon release in immune cells, a pathway linked to psoriasis.
Half-life: No reliable human elimination half-life for purified LL-37 was identified.
Related to LL-37
- KPV: An alpha-MSH fragment studied for gut inflammation in animals, with no human dosing trial.
- SS-31 (elamipretide): A peptide approved for Barth syndrome muscle strength; benefit needs confirmation and broader energy benefits remain unproven.
- Thymosin alpha-1: An immune-signaling peptide with overseas approvals and mixed trial results.
Sources
- 21 CFR 216.23 — Bulk drug substances that can be used to compound drug products in accordance with section 503A of the Federal Food, Drug, and Cosmetic Act., Office of the Federal Register · eCFR · 2026
- Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act, FDA · FDA · 2026
- Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks, FDA · FDA · 2026
- Concerns regarding the public health risks associated with unapproved peptide products, Therapeutic Goods Administration and Chief Medical Officer · Therapeutic Goods Administration · 2026
- Medicines, European Medicines Agency · European Medicines Agency · 2026
- MHRA Products | Home, MHRA · MHRA · 2026
- The 2026 Prohibited List, World Anti-Doping Agency · WADA · 2026
- Think twice before injecting peptides bought online: unauthorized products can seriously harm you, Health Canada · Health Canada · 2026
- Unapproved peptide product promoters and suppliers are put on notice, Therapeutic Goods Administration · 2026
- Bulk Drug Substances Nominated for Use in Compounding Under Section 503B of the Federal Food, Drug, and Cosmetic Act, FDA · FDA · 2025
- Sterile Drug Products Produced by Aseptic Processing — Current Good Manufacturing Practice, FDA · 2004
- Efficacy and safety of Oral LL-37 against the Omicron BA.5.1.3 variant of SARS-COV-2: A randomized trial., Zhao Y et al. · Journal of medical virology · 2023
- Efficacy of LL-37 cream in enhancing healing of diabetic foot ulcer: a randomized double-blind controlled trial., Miranda E et al. · Archives of dermatological research · 2023
- Evaluation of LL-37 in healing of hard-to-heal venous leg ulcers: A multicentric prospective randomized placebo-controlled clinical trial., Mahlapuu M et al. · Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society · 2021
- Preliminary evaluation of the safety and efficacy of oral human antimicrobial peptide LL-37 in the treatment of patients of COVID-19, a small-scale, single-arm, exploratory safety study, Zhang H et al. · medRxiv · 2020
Sources checked: 2026-10-18.
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