Peptide Graded

LL-37

Is LL-37 safe?

Topical only; no injected human data

CAnimal and cell studiesNot approvedas of 2026-10-26

In the two topical trials, LL-37 was well tolerated at the concentrations used. There were no serious drug-related events. No data exist on injected LL-37 in humans. So the side effects of the injected form are unknown. 1516

The lab and mechanism studies raise specific concerns for injected use. LL-37 drives interferon production and T cell autoimmunity in psoriasis. It promotes inflammation in rosacea. It also stimulates blood vessel growth in a way linked to tumor biology in ovarian, breast and lung cancers. No one has tested whether added LL-37 worsens any of these in people. That is the point. The FDA's earlier Category 2 placement cited the lack of safety data. 28111213

Read the full LL-37 page

More on LL-37

Citations

  1. Biochem Biophys Res Commun 2020: LL-37 antiviral and immunomodulatory activity doi.org
  2. FDA: Certain bulk drug substances for use in compounding may present significant safety risks fda.gov
  3. FDA: Bulk drug substances nominated for use in compounding under section 503A, category list fda.gov
  4. FDA: Pharmacy Compounding Advisory Committee meetings fda.gov
  5. De Yang 2000, J Exp Med: LL-37 uses FPRL1 to chemoattract neutrophils, monocytes and T cells pubmed.ncbi.nlm.nih.gov
  6. Sorensen 2001, Blood: hCAP-18 is processed to LL-37 by proteinase 3 pubmed.ncbi.nlm.nih.gov
  7. Heilborn 2003, J Invest Dermatol: LL-37 in re-epithelialization of skin wounds and lacking in chronic ulcers pubmed.ncbi.nlm.nih.gov
  8. Salvado 2013, Arterioscler Thromb Vasc Biol: LL-37 induces angiogenesis via PGE2-EP3 signaling pubmed.ncbi.nlm.nih.gov
  9. Gombart 2005, FASEB J: CAMP gene is a direct target of the vitamin D receptor pubmed.ncbi.nlm.nih.gov
  10. Liu 2006, Science: Toll-like receptor triggering of a vitamin D-mediated antimicrobial response pubmed.ncbi.nlm.nih.gov
  11. 2025, Front Immunol: Post-translational modifications of the autoantigen LL37 in psoriasis pubmed.ncbi.nlm.nih.gov
  12. Lande 2007, Nature: Plasmacytoid dendritic cells sense self-DNA coupled with antimicrobial peptide pubmed.ncbi.nlm.nih.gov
  13. Yamasaki 2007, Nat Med: Serine protease activity and cathelicidin promote skin inflammation in rosacea pubmed.ncbi.nlm.nih.gov
  14. De Smet 2005, Biotechnol Lett: Human antimicrobial peptides, defensins, cathelicidins and histatins pubmed.ncbi.nlm.nih.gov
  15. Gronberg 2021, Wound Repair Regen: LL-37 in hard-to-heal venous leg ulcers, randomized placebo-controlled trial pubmed.ncbi.nlm.nih.gov
  16. 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.