Does LL-37 work?
Not properly: animal or lab studies, or small uncontrolled human reports. One sore trial of 148 people was negative on its main goal.
Two randomized placebo-controlled trials exist, both of LL-37 applied topically to chronic wounds: 148 patients with venous leg ulcers (negative on the primary endpoint) and a smaller diabetic foot ulcer trial. The injected 'immune support' use sold online has no human data at all. The rest of the human literature is observational work on the body's own LL-37 in wounds, psoriasis, and rosacea, plus cell and mouse mechanism studies. For the use it is sold for, that is C. 1516
The HEAL LL-37 trial randomized 148 patients with hard-to-heal venous leg ulcers. They got one of two strengths of LL-37 gel or placebo, along with compression. In the full group, healing did not differ significantly. A post hoc subgroup had ulcers of at least 10 square centimeters. They did better on LL-37. The authors flagged this for a follow-up trial. A smaller double-blind trial in Jakarta treated mildly infected diabetic foot ulcers for four weeks with LL-37 cream or placebo. It found consistently more granulation tissue in the LL-37 group. Inflammatory cytokines and bacterial counts did not drop as expected. 1516
Studies of patients show why the peptide cuts both ways. Chronic ulcers lack LL-37 at the wound edge. That supports the wound-healing rationale. But in psoriasis, LL-37 binds the patient's own DNA and RNA. It turns them into triggers for plasmacytoid dendritic cells. T cells that attack the body's own tissue also target it. In rosacea, abnormal processing produces LL-37 fragments that drive the facial inflammation. 7111213
Evidence checklist
- Randomised controlled trial Two topical wound RCTs
- Human study over 100 people Venous ulcer trial, 148 patients
- More than one research group Article does not say who ran the trials
- Clinical outcomes, not surrogate markers Ulcer healing mixed; one negative
- Human safety data beyond case reports Topical only; no injected human data
More on LL-37
Citations
- Biochem Biophys Res Commun 2020: LL-37 antiviral and immunomodulatory activity doi.org
- FDA: Certain bulk drug substances for use in compounding may present significant safety risks fda.gov
- FDA: Bulk drug substances nominated for use in compounding under section 503A, category list fda.gov
- FDA: Pharmacy Compounding Advisory Committee meetings fda.gov
- De Yang 2000, J Exp Med: LL-37 uses FPRL1 to chemoattract neutrophils, monocytes and T cells pubmed.ncbi.nlm.nih.gov
- Sorensen 2001, Blood: hCAP-18 is processed to LL-37 by proteinase 3 pubmed.ncbi.nlm.nih.gov
- Heilborn 2003, J Invest Dermatol: LL-37 in re-epithelialization of skin wounds and lacking in chronic ulcers pubmed.ncbi.nlm.nih.gov
- Salvado 2013, Arterioscler Thromb Vasc Biol: LL-37 induces angiogenesis via PGE2-EP3 signaling pubmed.ncbi.nlm.nih.gov
- Gombart 2005, FASEB J: CAMP gene is a direct target of the vitamin D receptor pubmed.ncbi.nlm.nih.gov
- Liu 2006, Science: Toll-like receptor triggering of a vitamin D-mediated antimicrobial response pubmed.ncbi.nlm.nih.gov
- 2025, Front Immunol: Post-translational modifications of the autoantigen LL37 in psoriasis pubmed.ncbi.nlm.nih.gov
- Lande 2007, Nature: Plasmacytoid dendritic cells sense self-DNA coupled with antimicrobial peptide pubmed.ncbi.nlm.nih.gov
- Yamasaki 2007, Nat Med: Serine protease activity and cathelicidin promote skin inflammation in rosacea pubmed.ncbi.nlm.nih.gov
- De Smet 2005, Biotechnol Lett: Human antimicrobial peptides, defensins, cathelicidins and histatins pubmed.ncbi.nlm.nih.gov
- Gronberg 2021, Wound Repair Regen: LL-37 in hard-to-heal venous leg ulcers, randomized placebo-controlled trial pubmed.ncbi.nlm.nih.gov
- 2023, Arch Dermatol Res: LL-37 cream in diabetic foot ulcer, randomized double-blind controlled trial pubmed.ncbi.nlm.nih.gov
Reference information only, not medical advice. Drawn from the LL-37 article, fact-checked against the cited sources. No dosing anywhere on this site.