Who should not take LL-37?
Documented caution flags for LL-37 include mast cell activation syndrome (MCAS) and pregnancy / nursing. This is not exhaustive, and absence from this list is not a safety clearance. Anyone pregnant, nursing, or managing a serious medical condition should only consider it under a doctor's care, and safety data for LL-37 is limited.
Documented caution flags for LL-37
- Mast cell activation syndrome (MCAS)
- Pregnancy / nursing
Reported side effects to weigh
- Mild flu-like symptoms early
- Injection-site irritation
- Mast-cell activation in sensitive users
References
- LL-37, the truncation product of cathelicidin, antimicrobial review — Wang G, Curr Top Med Chem, 2020
- Human antimicrobial/host defense peptide LL-37 may prevent the spread of a local infection through multiple mechanisms: an update — Svensson D et al., Inflammation Research, 2025
- Significance of the LL-37 Peptide Delivered from Human Cathelicidin in the Pathogenesis, Treatment, and Diagnosis of Sepsis — Mankowska A et al., Archivum Immunologiae et Therapiae Experimentalis, 2025
Pepdex is an editorial reference, not medical advice. Peptides vary in legal and approval status by country, many are research compounds without full human safety data. Talk to a qualified clinician before starting anything.
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Last updated 2026-06-15.