What Is It?
Two leucines, 37 amino acids. Your body makes it — it's the only cathelicidin humans produce. Made by neutrophils, macrophages, and epithelial cells. Released at sites of infection or injury. Recently removed from FDA Category 2 restrictions (April 2026).
How Does It Work?
You cut yourself. Bacteria enter the wound. Within minutes, your neutrophils arrive carrying an inactive precursor: hCAP-18. An enzyme cuts hCAP-18. LL-37 is released. Only at the wound. Only when needed. Only the amount required. Your body keeps it locked until the moment it has to fire. Disrupts bacterial membranes, breaks biofilms, neutralizes endotoxins, stimulates wound healing, and modulates immune response.
Primary Benefits (research suggests)
- Active against 43+ clinical bacterial strains including drug-resistant species
- Breaks biofilms that antibiotics can't penetrate
- Promotes wound healing via VEGF signaling
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- Dose-dependent cytotoxicity — high doses kill bacteria AND host cells.
- Elevated LL-37 implicated in rosacea and psoriasis.
- Clinical analogs keep failing (KR-12, omiganan). Full LL-37 fails trials due to instability and toxicity.
- Counterfeit market rampant.
- For research purposes only.
Research Sources
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