LL-37 is a research-stage peptide with no approved human dosing. The only human data come from topical wound trials; injected amounts discussed online are anecdotal and uncited. This page is for education, not a personal protocol.
What has actually been dosed in a person
LL-37 has been given to humans in two published trials, both as a topical preparation applied to hard-to-heal venous leg ulcers, and both expressed as a concentration in milligrams per millilitre rather than a systemic milligram dose. No published study has administered LL-37 by injection to a person, so there is no human injectable dose to report — not a low one, not a cautious one, none.
The trial concentrations, and the inverted curve
The 2014 first-in-man study (Grönberg et al., Wound Repair and Regeneration; PMID 25041740) enrolled 34 participants, ran a 3-week open-label placebo run-in, then a 4-week randomized double-blind phase of twice-weekly topical application at 0.5, 1.6, or 3.2 mg/mL, followed by 4 weeks of follow-up. The reported results:
- 0.5 mg/mL — healing rate constant roughly sixfold higher than placebo (p=0.003); mean ulcer area down 68%.
- 1.6 mg/mL — roughly threefold higher than placebo (p=0.088); mean ulcer area down 50%.
- 3.2 mg/mL — no difference in healing versus placebo.
The lowest concentration performed best and the highest performed like nothing at all. That is not a dosing curve where more is more, and it matches the biophysics: LL-37 is cytotoxic to eukaryotic cells at 13–25 µM while killing bacteria near 5 µM (PMID 9452503).
The follow-on phase IIb, HEAL LL-37 (PMID 34687253), carried forward only the two lower strengths, 0.5 and 1.6 mg/mL, in 148 patients alongside compression therapy — and found no significant healing benefit over placebo in the full population, with a post hoc signal limited to wounds of at least 10 cm². Both strengths were well tolerated.
What community sources report
Commonly reported schemas in peptide-community material, none traceable to a published study:
- Subcutaneous amounts described somewhere between tens of micrograms and a few milligrams per administration, with wide disagreement between sources.
- No consistent frequency, cycle length, or endpoint.
- Framing that treats a higher amount as a stronger effect — which the trial data specifically contradict.
These figures describe what people report doing. They are not doses in any evidentiary sense.
Route and handling
The studied route is topical application to an open wound bed, twice weekly, in a formulated preparation. In laboratory settings LL-37 is supplied as a lyophilized powder and reconstituted; it is degraded by digestion if swallowed. Where a powder is reconstituted, the delivered amount is set by how much diluent is added, and syringe units measure volume rather than milligrams — a routine source of order-of-magnitude error.
One additional handling fact matters for this peptide specifically: human serum inhibits both its antibacterial and its cytotoxic activity (PMID 9452503), so behaviour in a vial, on a wound, and in circulation are three different situations.
Why the "how much" question is unusually consequential here
For most research peptides, uncertainty about dose means uncertainty about whether anything happens. For LL-37 it also means uncertainty about which direction. The same peptide is used experimentally to induce injury models, and elevated cathelicidin is the mechanism behind rosacea inflammation (PMID 17676051) and psoriatic interferon activation (PMID 17873860). With no approved label, no verified product concentration, and a documented inverted dose-response in the one trial that tested a range, any concrete decision belongs inside a formal research protocol with qualified oversight.