LL-37
LL-37 is the only cathelicidin-family antimicrobial peptide produced in humans, generated by cleavage of the precursor protein hCAP18 and expressed by immune cells, epithelial cells, and skin. It has been studied for its dual role in direct antimicrobial defense and in modulating innate immune responses and wound healing. Research spans infectious disease, dermatology, and inflammatory bowel conditions. LL-37 also has a complex relationship with inflammation, since dysregulated levels have been associated with autoimmune conditions such as psoriasis and lupus, making its net effects context-dependent.
Reported benefits
- Studied for broad-spectrum antimicrobial defense
- Explored for supportive roles in wound healing and tissue repair
- Investigated for immune modulation in infection contexts
- May support skin barrier function research
How it works
LL-37 disrupts microbial cell membranes directly, contributing to broad-spectrum antimicrobial activity against bacteria, fungi, and some viruses. It also engages immune cell receptors, including formyl peptide receptor 2, to modulate chemotaxis, cytokine release, and wound-healing processes such as angiogenesis and re-epithelialization. Because it can promote or dampen inflammation depending on tissue context and concentration, its immunomodulatory role is considered more nuanced than purely anti-inflammatory.
Dosing ranges
| Tier | Dose | Frequency |
|---|---|---|
| Low | 50 mcg | daily |
| Moderate | 100 mcg | daily |
| High | 200 mcg | daily |
Estimate your dose
Dose estimator
Educational estimate for LL-37, scaled to body size. Not medical advice.
Read before using
This tool produces a rough, educational estimate by scaling commonly-published research ranges to lean body mass. It is not a prescription, medical advice, or a substitute for a licensed clinician. Most peptides use fixed dosing, not weight-based dosing. Individual needs vary. You are solely responsible for how you use this information.
Mixing & syringe units
Target dose follows the estimate above. Change it there, or edit it directly below.
Reconstitution calculator
How much water to add and how many insulin-syringe units to draw for LL-37. Educational only.
Draw to this mark
2units
= 0.02 mL for a 100 mcg dose
Concentration
5,000 mcg/mL
Doses per vial
100
A U-100 syringe reads 100 units per mL. This is a reconstitution math helper only, not a prescription or dosing advice. Verify every calculation and consult a qualified healthcare provider.
Possible side effects
Stacking notes
Sometimes discussed alongside healing-focused peptides such as BPC-157; caution urged given LL-37's dual pro- and anti-inflammatory potential
Common protocols
Common questions
What is LL-37 used for?
LL-37 is the only cathelicidin-family antimicrobial peptide produced in humans, generated by cleavage of the precursor protein hCAP18 and expressed by immune cells, epithelial cells, and skin. It has been studied for its dual role in direct antimicrobial defense and in modulating innate immune responses and wound healing. Research spans infectious disease, dermatology, and inflammatory bowel conditions. LL-37 also has a complex relationship with inflammation, since dysregulated levels have been associated with autoimmune conditions such as psoriasis and lupus, making its net effects context-dependent. Reported benefits include studied for broad-spectrum antimicrobial defense, explored for supportive roles in wound healing and tissue repair, investigated for immune modulation in infection contexts.
What is a typical LL-37 dose?
Reported ranges run 50-200 mcg. A low protocol is 50 mcg daily, and a high protocol is 200 mcg daily. This is reference information, not a dosing recommendation.
What is the half life of LL-37?
Short, estimated at under 1 hour, though local tissue effects may persist longer. That is what sets the dosing frequency, and it is why the timing guidance is morning.
How is LL-37 administered?
Subcutaneous: into fat, under the skin.
How long is a LL-37 cycle?
2-4 weeks on, followed by 4 weeks off. Short courses are typically favored given its complex, context-dependent immune signaling role
What are the side effects of LL-37?
Reported side effects include injection site irritation, theoretical risk of pro-inflammatory effects in susceptible individuals given its complex immune role, limited human dosing and long-term safety data, possible flushing. Evidence level for this compound is moderate evidence.
Partner offer · $20 off
When did you last
check your blood work?
Regular blood work catches changes early. At-home collection with free pickup, 50+ biomarkers, and results in 72 hours.
- 1Order your kitTakes two minutes online, $20 off with this link.
- 2Collect at homePainless draw with free home pickup, no lab visit.
- 3Results in 72 hours50+ biomarkers with clear optimal ranges.
Partner offer · opens rythm.health
Educational use only, not medical advice. This profile is provided for research and educational purposes. LL-37 may be a research compound or a prescription medication; nothing here is intended to diagnose, treat, cure, or prevent any disease. Dosing figures reflect commonly-published research ranges, not a prescription. Consult a qualified healthcare provider before making any health decision. Read the full disclaimer →