LL-37 is a thirty seven amino acid antimicrobial peptide that your own body produces, the active fragment of a protein called cathelicidin. It is part of innate immunity, the fast general-purpose defence system that acts before the more targeted immune response engages, and it can disrupt bacterial membranes directly as well as signalling to other immune cells. It is genuinely important biology and an active research area, particularly given concerns about antibiotic resistance. It is not an approved treatment. Human studies are small and academic, no completed randomised controlled trial establishes it as a therapy, and treating an endogenous immune peptide as a substitute for an antibiotic is not supported by anything published.