LL37
Human cathelicidin antimicrobial peptide with broad-spectrum antimicrobial activity and immunomodulatory effects.
Regulatory status (as of Sept 2026)
Slated for a PCAC review (503A bulks) before end of Feb 2027. Not FDA-approved.
See the FDA peptide regulatory tracker · Read our July 27, 2026 dispatch on the FDA PCAC peptide vote2 studies referenced · Last reviewed Oct 1, 2026 · Reviewed by The Peptide Dispatch Editorial Team · How we research & label content
LL-37 is an investigational compound tested in mid-stage (phase 2) human trials. Human cathelicidin antimicrobial peptide with broad-spectrum antimicrobial activity and immunomodulatory effects.
| Half-life | Not established in published research |
|---|---|
| How it's given in studies | Subcutaneous injection |
| Research stage | Phase 2 |
| Dosing | Published research: Topical 0.5, 1.6 or 3.2 mg/mL applied twice weekly to venous leg ulcers in humans (phase 1/2, n=34) detailsTopical 0.5, 1.6 or 3.2 mg/mL applied twice weekly to venous leg ulcers in humans (phase 1/2, n=34); 0.5 or 1.6 mg/mL topical (phase 2b, n=148)Community-reportedCommunity-reported: 100–200 mcg, subcutaneous injection |
Published-research dosing is what was given in the cited studies (species and units as reported). Community-reported dosing is what users describe, not from clinical studies. Neither is a recommendation. Not medical advice.
Where each point comes from: Clinicalhuman trials and FDA labels Lab / animalrodent, cell and ex vivo studies Community-reporteduser experience and commonly used protocols, not from clinical studies
In plain terms: It is a natural germ-fighting peptide made by the body; results in wound-healing trials were mixed. Human cathelicidin antimicrobial peptide; its proposed actions are direct antimicrobial activity and immune-cell activation. Applied topically to hard-to-heal venous leg ulcers, it showed faster healing rates at some doses in a first-in-human RCT (n=34; Grönberg 2014), but the larger phase 2b RCT (n=148) found no significant improvement in healing in the full study population (Mahlapuu 2021).
How to read this: Each item below is an effect observed in research subjects in the cited studies — think of Dexter, our stand-in research subject. These are findings from the literature, not results you should expect, and not medical advice.
Community-reportedIn user communities, LL-37 is typically run at 100–200 mcg (subcutaneous injection). This is not a recommendation.
Side effects reported in studies are listed separately below.
Community reports are anecdotal, vary widely in product quality and purity, and are not medical advice. Talk to a licensed provider.
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| Peptide | Half-Life | Route | Research Status |
|---|---|---|---|
| LL-37 | Unknown | Subcutaneous injection | Phase 2 |
| KPV | No published PK data found | Subcutaneous injection, Oral, Topical | Preclinical (animal) |
| Thymalin | No published PK data found | Intramuscular injection | Approved outside US |
| Thymopoietin II Fragment (TP-1) | Unknown | Subcutaneous injection | Preclinical (animal) |
| Thymosin Alpha-1 | No published human PK data found; ~3 h for native Tα1 in rats (Shen 2019). Literature describes a 'short plasma half-life' requiring twice-weekly s.c. dosing. | Subcutaneous injection | Approved outside US |
Values reflect figures reported in published research. Compare any peptides side-by-side →
This peptide belongs to the Immune category. View All Immune Peptides
Healing
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Dosing, half-life figures, and mechanism descriptions on this page are compiled from peer-reviewed published research, with the species and study type stated where reported. Figures labeled “Dosing used in published research” describe what was given in those studies and do not constitute dosing recommendations for any human use. Each cited paper is listed with DOI and PubMed links in the References section above. Found an error? Contact us.