Immune & Thymic

LL-37

Also known as Cathelicidin · CAP-18 fragment · hCAP18

Emerging researchSubcutaneous injectionTopicalOral (investigational)NOT FDA-approved; research/investigational. Currently on the FDA 503A Category 2 list (substances raising significant safety concerns) and slated for Pharmacy Compounding Advisory Committee review.

LL-37 is the only member of the cathelicidin family of antimicrobial peptides found in humans, produced by immune and epithelial cells. It has direct activity against bacteria, viruses, and fungi, disrupts biofilms, neutralizes bacterial toxins, and helps recruit immune cells and support wound closure. It also acts as an immune signaling molecule, though research links excessive LL-37 to inflammatory and autoimmune conditions such as psoriasis and rosacea, making its biology context-dependent.

Studied / used for

Studied for antimicrobial and antibiofilm activity
Studied for immune signaling and wound healing
Studied as a potential adjunct in infection and wound contexts

Commonly reported side effects

Mild injection-site redness (erythema)
Possible exacerbation of inflammatory skin conditions (e.g., rosacea, psoriasis)
Limited human safety data overall

Emerging research. Active research; human evidence still developing. This reflects the strength of the research base, not effectiveness or a recommendation.

Not medical advice.

This is an educational reference. Peptalk does not recommend, prescribe, endorse, or rate any compound, and provides no dosing information. Do not start, stop, or change any peptide, hormone, supplement, or therapy based on this page. All clinical decisions must be made with your licensed healthcare provider.

← Back to all compounds