Also known as: Cathelicidin
The only human cathelicidin, a natural antimicrobial peptide made by skin and immune cells.
Educational reference, not medical advice. Many compounds here are not approved, and products sold as research chemicals are not checked for purity. Plan any use with a licensed clinician.
How it works
Punctures bacterial membranes, breaks up biofilms, and helps coordinate immune cells. Also promotes wound closure.
Evidence by goal
| Goal | Grade | What the grade means |
|---|---|---|
| Immune & infections | C | Limited human data, case series or practitioner reports |
| Skin, hair & appearance | C | Limited human data, case series or practitioner reports |
| Gut health | D | Animal or cell studies only |
At a glance
- Route
- Subcutaneous or topical
- Half-life
- Short
Reported dosing
50 to 125 mcg daily (practitioner reports).
Timing: Once daily.
Cycle: 2 to 6 weeks.
From approved labels where they exist, otherwise from published trials and practitioner reports.
Side effects
- Injection-site redness and itching
- Can worsen inflammatory skin conditions
Who should avoid it
- Rosacea or psoriasis (LL-37 drives these conditions)
- Autoimmune disease
Often combined with
With thymosin alpha-1 for immune support.
Key findings
A small trial of topical LL-37 sped healing of venous leg ulcers. Injectable use is based on practitioner reports.
Where it is legal (Oct 2026)
| US | Not approved |
|---|---|
| Canada | Not approved |
| Mexico | Not approved |
| EU | Not approved |
Sources
Open LL-37 in the Peptide Guide Compare all peptides by goal
Last reviewed November 2026. Regulatory status reflects the US unless noted and changes often.