What the studies show
Topical gel well tolerated in both trials; serious adverse events in 7.4% of the phase 2b population, none attributed to the drug. Nothing is known about injected use.
A few small or poorly-controlled human studies. Enough to be interesting; not enough to count on. Most of what gets called “clinically proven” online lives here.
- 1Mahlapuu M, et al. Evaluation of LL-37 in healing of hard-to-heal venous leg ulcers: a multicentric prospective randomized placebo-controlled clinical trial.Wound Repair Regen, 2021148 patients, phase 2b; primary endpoint not met.
In context
LL-37 is the only cathelicidin peptide humans make — a 37-amino-acid antimicrobial produced by skin, gut and immune cells that kills bacteria and signals inflammation and repair. The human evidence is two randomised trials of a topical gel on venous leg ulcers: a 34-patient phase 2a that found faster healing, and a 148-patient phase 2b that did not, except in a subgroup of large wounds. Nothing supports the injected 'immune' or 'anti-inflammatory' uses sold online, and injected LL-37 is pro-inflammatory in the laboratory.
LL-37 is not approved. Legal status differs by country — see the regulation section or the jurisdiction pages.
Questions
Is LL-37 proven to cause safety?
What studies are behind the grade?
Is LL-37 approved for this?
Other outcomes for LL-37
- CVenous leg ulcer healing (topical)2 RCTs (n=34, n=148)
- DAntimicrobial action in people0 controlled
- DSystemic 'immune support' or anti-inflammatory use0
Reviewed 3 September 2026. Grades count human evidence only; see how LYO grades. Not medical advice. Correct this page →