LL-37 (Cathelicidin)

The practical verdict is simple: LL-37 is a fascinating molecule with one promising topical use and a genuine double-edge. If you are drawn to it, the only route with human evidence is topical wound care, and even that rests on one small trial of 34 people. For the injectable systemic use the grey market sells, you would be dosing a confirmed autoimmune trigger and documented cancer growth factor with zero human efficacy data behind it, which is a poor trade no matter how good the mechanism reads. That balance is the honest read: a rich, broad mechanism limited by thin human proof and a real intrinsic risk that falls hardest on people with any autoimmune or cancer history. Watch the research closely, but do not mistake an impressive mechanism for a proven therapy.

✅ Best for: Researchers and clinicians who want to understand a uniquely versatile host-defense peptide and its role in immunity, wound healing, and disease. People specifically interested in topical wound care who accept that the evidence is one small trial and that the lowest dose worked best, per Gronberg 2014. People who would rather raise their own cathelicidin the proven way, by correcting vitamin D, per Liu 2006. Anyone with no autoimmune or cancer history who still wants to follow this peptide's science closely before any use.

❌ Avoid if: You have any personal or family history of psoriasis, lupus, or rheumatoid arthritis, since LL-37 is a confirmed autoimmune trigger and autoantigen, per Lande 2014. You have any active, prior, or suspected cancer, since it is a documented growth factor for lung, ovarian, and breast cancer cells, per von Haussen 2008. You want a proven systemic immune or repair peptide, because human efficacy data for injectable LL-37 is zero. You cannot verify source quality, since it is sold unregulated as a research chemical with no purity or sterility guarantee.