Educational content only — this is not medical advice. Nothing here is a recommendation to buy, obtain, or use LL-37. Talk to a licensed clinician before making health decisions.
What it is
LL-37 is a 37-amino-acid cationic peptide released from the C-terminus of the human cathelicidin antimicrobial peptide (hCAP-18/CRAMP). It is produced by epithelial cells, neutrophils, and macrophages. In addition to direct microbe killing, it modulates inflammation, promotes angiogenesis, and influences immune-cell recruitment.
What the evidence shows
Evidence is predominantly preclinical. LL-37 shows broad antimicrobial activity in vitro and accelerates wound healing in animal models. It has been investigated in contexts ranging from diabetic wounds to psoriasis, cystic fibrosis, and periodontal disease. Translational human studies are limited; no randomized controlled trial has established efficacy for a specific approved indication.
Risks & unknowns
At high concentrations LL-37 can be cytotoxic to mammalian cells and may promote inflammation or atherosclerosis in some models. Its role in cancer is complex — it appears protective in some contexts and potentially tumor-promoting in others. Safety of exogenous LL-37 in humans is not established.
Legal / regulatory status
LL-37 is not FDA-approved. It is sold as a research peptide only. Its use in sport has not been singled out by WADA as of 2026, but peptide hormones and growth factors are broadly prohibited under S2.