- subcutaneous
- topical
LL-37
LL-37 (Cathelicidin Antimicrobial Peptide / hCAP18 C-terminal fragment)
LL-37 at a glance
Nomination withdrawnHow studies gave it
Injected into the fat under the skin, or applied to the skin
Evidence on this page
3 peer-reviewed papers, published 2006 to 2014
FDA compounding lists
It was nominated for compounding use and the nomination was withdrawn.
What it is
The sole human member of the cathelicidin family of antimicrobial peptides, cleaved from the 18 kDa precursor protein hCAP18. LL-37 is a cationic, amphipathic α-helical peptide with broad-spectrum antimicrobial activity against bacteria (including MRSA), fungi, and viruses, as well as immunomodulatory and wound-healing properties.
It has been studied in Phase I/IIb human trials for topical wound healing (venous leg ulcers, diabetic foot ulcers) and intratumoral melanoma injection. Its expression is transcriptionally regulated by vitamin D. No clinical trials have evaluated subcutaneous systemic injection — the route most discussed in biohacking communities.
Published research
LL-37 has demonstrated clinical efficacy in topical wound healing: a Phase I/IIa trial (Grönberg et al., 2014) in 34 venous leg ulcer patients showed a ~6-fold higher healing rate at 0.5 mg/mL versus placebo. A Phase IIb (HEAL) trial in 148 patients confirmed benefit in ulcers >10 cm². A diabetic foot ulcer RCT (2023) showed enhanced granulation tissue formation with LL-37 cream.
A Phase I melanoma trial tested intratumoral injection at MD Anderson. Preclinically, LL-37 demonstrates antimicrobial activity against >38 bacterial species, anti-biofilm properties, immunomodulatory effects (FPRL-1 chemotaxis, pDC activation), and context-dependent pro/anti-tumor activity. All human trial data involves topical or intratumoral administration; subcutaneous systemic dosing has zero clinical trial support.
What the terms on this page mean7 termsHide
- peptide
- A short chain of amino acids, the building blocks of proteins.
- Phase 1
- The first test in people, usually a small group, looking mainly at safety rather than at whether it works.
- clinical trial
- A study that tests something in people under a written plan, with results recorded.
- subcutaneous
- Into the fat layer just under the skin.
- efficacy
- Whether something works under trial conditions, which is not the same as in daily use.
- placebo-controlled
- Part of the group receives an inactive substitute for comparison.
- randomised controlled trial
- A trial that assigns people to treatment or control by chance, which is what lets it separate an effect from luck.
Compounding status
Nomination withdrawn- FDA lists it as
- Cathelicidin LL-37
- What that means
- These substances are not eligible for the policy that applies to substances in category 1. FDA would consider taking action against a compounder for compounding drug products with this bulk drug substance under its general enforcement policies.
Source: Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks, FDA. Content current as of 2026-04-22; read 2026-09-05. This describes what a compounding pharmacy may supply. It is not advice about your own use.
Also given subcutaneous
- Melanotan IIMelanotan II (Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2)Nomination withdrawn
- MOTS-cMitochondrial Open Reading Frame of the 12S rRNA Type-cNomination withdrawn
- Palmitoyl Pentapeptide-4 (Matrixyl)Palmitoyl-Lys-Thr-Thr-Lys-Ser (Pal-KTTKS)Not on either FDA list
- PE-22-28PE-22-28 (Spadin Analog, Sortilin Propeptide Fragment 22-28)Not on either FDA list
- Pentosan Polysulfate (PPS)Pentosan Polysulfate SodiumNot on either FDA list
- PT-141 (Bremelanotide)Bremelanotide (Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH)Not on either FDA list
Where this came from3 referencesHide
Each one was resolved at PubMed and confirmed to be the work this page cites. Author, title, journal and year come from the PubMed record, not from the page text.
- Treatment with LL-37 is safe and effective in enhancing healing of hard-to-heal venous leg ulcers: a randomized, placebo-controlled clinical trial
Grönberg A, et al.. Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society (2014). PMID 25041740.
- LL-37, the only human member of the cathelicidin family of antimicrobial peptides
Dürr UH, Sudheendra US, Ramamoorthy A. Biochimica et biophysica acta (2006). PMID 16716248.
- A comprehensive summary of LL-37, the factotum human cathelicidin peptide
Vandamme D, et al.. Cellular immunology (2012). PMID 23246832.
About this page
Reviewed 2026-08-11. This page reports what published studies and FDA documents say. It carries no dose, cycle length or stack, and it does not tell you whether a substance is appropriate for you. Side-effect reports circulating on forums are self-reported rather than measured, so they are not republished here.
See the editorial policy for how corrections are handled.