LL-37
Cathelicidin · hCAP-18 fragment
The body's own antimicrobial peptide, studied for infection defence and wound healing.
Class
Human cathelicidin antimicrobial peptide
Half-life
Short
Evidence
In-vitro / mechanistic
In-vitro / mechanistic
Cell-culture or mechanistic work only. No meaningful in-vivo human evidence exists.
Overview
LL-37 is the only human cathelicidin — a naturally produced antimicrobial peptide that forms part of innate immunity. It punches holes in bacterial membranes, neutralises bacterial toxins, and also has signalling roles in wound healing and inflammation modulation.
Its breadth is what makes it interesting: activity against bacteria (including some antibiotic-resistant strains), fungi, and viruses, plus a role in recruiting immune cells and closing wounds. Low LL-37 levels are associated with certain chronic infections and poor wound healing.
Research interest is real, but human therapeutic use is preclinical — LL-37 is unstable, can be pro-inflammatory or even harmful at high concentrations, and has been implicated in some inflammatory skin conditions like rosacea. It is sold as a research chemical with essentially no human dosing evidence.
How it works
- Disrupts microbial cell membranes, killing bacteria, fungi, and enveloped viruses.
- Neutralises bacterial endotoxin (LPS), dampening septic inflammation.
- Recruits and activates immune cells (chemotactic activity).
- Promotes angiogenesis and re-epithelialisation in wound healing.
What the research shows
Researched effects
- Broad antimicrobial activity in vitro, including against resistant organisms
- Endotoxin neutralisation in preclinical sepsis models
- Wound-healing and angiogenic effects
- Implicated (negatively) in inflammatory skin disease at high levels
Limitations & what it won't do
- No controlled human therapeutic trials.
- Can be pro-inflammatory or cytotoxic at higher concentrations — the dose-response is delicate.
- Associated with rosacea and some autoimmune activity when dysregulated.
- Not FDA approved.
Dosing protocols
These ranges reflect published trials and community protocols. They are reference information, not a prescription. Doses are per injection unless noted.
Community protocol (limited basis)
100–500 mcgThere is little human evidence to anchor a dose. Documented for reference with a strong caution about its pro-inflammatory potential.
Reconstitution & measuring your dose
Handling
- Typical vial sizes
- 5 mg
- Suggested BAC water
- 2 mL
- Storage
- Lyophilised powder refrigerated at 2–8 °C, protected from light.
- After reconstitution
- Reconstituted: approximately 20–30 days refrigerated.
Why 2 mL? A 5 mg vial in 2 mL yields 2500 mcg/mL — 250 mcg lands on 10 units of a U-100 syringe.
Dose calculator
Draw to
4units
= 0.04 mL · 25 mcg per unit
Concentration
2500 mcg/mL
Doses per vial
50
Side effects
Common
- Injection-site inflammation (can be significant given its pro-inflammatory nature)
- Redness and swelling
Serious / rare
- Pro-inflammatory reactions at higher doses
- Potential to aggravate inflammatory skin or autoimmune conditions
Contraindications & interactions
Do not use if you have
- Pregnant, breastfeeding, or trying to conceive
No pregnancy safety data.
- Autoimmune condition
LL-37 is implicated in driving several autoimmune and inflammatory conditions. Best avoided in active autoimmune disease.
Use caution if you have
- Melanoma, atypical moles, or high skin-cancer risk
LL-37 has been studied in tumour biology with context-dependent effects; caution with skin cancer risk.
Medication interactions
- cautionImmunosuppressants / biologics — Immune-modulating effects may work against or unpredictably with immunosuppression.
What to monitor
- Inflammatory response, local and systemic
- Skin condition
Commonly combined with
References
- Vandamme D et al. — A comprehensive summary of LL-37, the human cathelicidinCellular Immunology 2012;280:22-35
Research & educational information only — not medical advice.
You must be 18 or older to use this site. The peptides described are presented as research chemicals intended for research purposes only. Most are not approved by the FDA for human use. Dosing ranges reflect what has appeared in the scientific literature or community protocols and are not prescriptions. Nothing here replaces evaluation by a licensed physician who knows your full medical history.
Want to know if LL-37 fits your goals and history?
The assessment cross-checks your medical history and medications against this and every other compound before it recommends anything.
Start the assessment