Also known as cathelicidin, hcap-18 (c-terminal peptide) · Wikipedia
LL-37 is the only human cathelicidin antimicrobial peptide, a 37-amino-acid amphipathic alpha-helix cleaved from the C-terminus of hCAP-18 by proteinase 3 in neutrophils and other cells. It is both a direct broad-spectrum antimicrobial against bacteria, fungi, and enveloped viruses and a potent immunomodulator with pro-healing actions on skin and mucosa. Synthetic LL-37 has been studied in Phase I/II topical trials for hard-to-heal venous leg ulcers and diabetic foot ulcers, with low doses showing benefit and high doses showing dose-limiting necrosis/inflammation (https://pmc.ncbi.nlm.nih.gov/articles/PMC9298190/). No LL-37 drug product is FDA-approved. Also known as: Cathelicidin; hCAP-18 (C-terminal peptide).
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Browse all vendorsMechanism of action
LL-37 is an amphipathic cationic alpha-helix that directly disrupts microbial membranes by electrostatic insertion and toroidal-pore formation, killing Gram-positive and Gram-negative bacteria, fungi, and enveloped viruses (https://pmc.ncbi.
Pharmacokinetic properties
Half-life
short - minutes in plasma due to proteolysis; longer at mucosal/skin sites
Routes
subcutaneous · topical · intranasal
Bioavailability
Highly susceptible to serum protease degradation. Local/topical delivery favored for skin and respiratory targets. Cationic, can bind albumin and lipids.
Amino-acid sequence
Leu-Leu-Gly-Asp-Phe-Phe-Arg-Lys-Ser-Lys-Glu-Lys-Ile-Gly-Lys-Glu-Phe-Lys-Arg-Ile-Val-Gln-Arg-Ile-Lys-Asp-Phe-Leu-Arg-Asn-Leu-Val-Pro-Arg-Thr-Glu-Ser
Use & research dosing
There is no standardized human SC dose. Self-experimentation protocols report 100-1000 mcg SC daily or every other day in short cycles, with no PK or efficacy validation. The most rigorous human data come from the HEAL LL-37 Phase IIb trial in venous leg ulcers (n=148): topical LL-37 at 0.5 or 1.6 mg/mL applied with compression therapy showed safety and a healing signal at the low dose, while the high dose was associated with ulcer necrosis and severe inflammatory reactions (https://pmc.ncbi.nlm.nih.gov/articles/PMC9298190/). A diabetic-foot-ulcer trial reported similar benefit with topical low-dose application (https://pmc.ncbi.nlm.nih.gov/articles/PMC10514151/).
Research-use framing only. SavePeptides sells nothing for human consumption. Doses above reflect reported research / self-experimentation ranges, not clinical recommendations.
LL-37 is genuinely controversial - it is simultaneously a pro-healing antimicrobial and a recognized driver of inflammatory skin and autoimmune disease via self-nucleic-acid sensing. Risk profile differs sharply by dose, route, and target tissue: low-dose topical for wound healing has the cleanest evidence, while high-dose or systemic use risks both cytotoxicity (HEAL trial high-dose arm) and autoimmune amplification. Subjects with psoriasis, lupus, or other type-I-interferon-driven autoimmune conditions should be considered contraindicated.
— SavePeptides editorial desk · last updated 2026-05-25
Cautions & contraindications
Research foundation
Facts verified
2026-05-25
Confidence
medium
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