Peptide library / Immune & defense / LL-37
LL-37
The only cathelicidin in humans, an antimicrobial and wound-healing peptide produced by skin and immune cells.
Full analysis available. LL-37 is under FDA compounding review, and we cover it in depth with the committee vote and our Peptide Evidence Index. Read the full LL-37 analysis →
Effects studied or claimed
What it is used or promoted for, and where each effect has actually been seen
- Antimicrobial defenceLab
- Healing of chronic leg ulcersSmall human studies
- Cancer immunotherapy, studiedSmall human studies
How it is thought to work
LL-37 punctures bacterial membranes and also signals immune cells, attracting them to infection and aiding wound repair.
What the evidence shows
A small phase 2 trial found faster healing of venous leg ulcers with topical LL-37. Roles in cancer and autoimmune disease are more mixed.
Safety and unknowns
At high levels it can be toxic to host cells and has been linked with skin inflammation in rosacea and psoriasis.
Regulatory status
Not FDA-approved. See our full LL-37 profile for the 2026 advisory committee review.
Regulatory status changes quickly. This entry was last reviewed on 27 October 2026. Confirm current status with the FDA before relying on it.
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General information, not medical advice. Do not buy or inject unregulated peptides.