LL-37
The Human Antimicrobial Peptide
A naturally occurring human antimicrobial peptide with broad-spectrum activity against bacteria, viruses, and fungi, plus wound healing properties.
Research Compound
About LL-37
LL-37 is the only human cathelicidin antimicrobial peptide and serves as a first-line defense against pathogens. It's naturally produced by immune cells, epithelial cells, and is found in sweat, saliva, and wound fluid. LL-37 has broad-spectrum activity against bacteria, viruses, and fungi, and can even disrupt bacterial biofilms—the protective matrices that make chronic infections so difficult to treat. Beyond its antimicrobial properties, LL-37 promotes wound healing, modulates inflammation, and supports tissue repair.
Mechanism of Action
LL-37 disrupts microbial membranes through electrostatic interactions with negatively charged pathogen surfaces, causing cell lysis. It also neutralizes bacterial endotoxins (LPS), reducing inflammatory responses to infection. LL-37 promotes wound healing by stimulating cell migration, angiogenesis, and tissue remodeling. Importantly, it can penetrate and disperse biofilms, making previously resistant infections susceptible to treatment.
How LL-37 Works in Your Body:
- Target Receptors: LL-37 binds to specific receptors that trigger downstream signaling cascades related to its primary benefits.
- Physiological Response: The body responds by modulating natural processes—whether hormone release, tissue repair, or cellular signaling—without replacing endogenous function.
- Timeline: Effects typically begin within 1-2 weeks, with optimal results seen over the recommended protocol duration.
Dosing Protocol
Frequency
1-2 times daily during infection or healing
Timing
Any time of day
Duration
2-4 weeks for acute use
Important Notes
50-100mcg subcutaneously for systemic effects. Can also be applied topically for wound healing. Sometimes nebulized for respiratory infections. Experimental protocols—work with knowledgeable practitioner.
Clinical Research
3 studies on LL-37
Antimicrobial Spectrum
LL-37 demonstrated activity against gram-positive and gram-negative bacteria, fungi, and enveloped viruses.
Antimicrobial Agents and Chemotherapy
Biofilm Disruption
LL-37 effectively disrupted established Pseudomonas aeruginosa biofilms at concentrations safe for human cells.
PLoS Pathogens
Wound Healing
LL-37 accelerated wound closure by 40% through enhanced cell migration and angiogenesis.
Journal of Investigative Dermatology
LL-37 in Practice
Who LL-37 is for
People with chronic, slow-healing wounds, persistent biofilm-driven infections, or treatment-resistant skin conditions where the body's own innate immunity is underperforming. LL-37 is also being studied in chronic Lyme protocols and antibiotic-resistant infections as part of multi-modal therapy under physician supervision.
Who should avoid it
Anyone with active autoimmune flare-ups (psoriasis, rosacea, lupus), pregnancy, or pediatric use. LL-37 is the human cathelicidin and overexpression has been implicated in inflammatory skin and joint diseases — the very immune activation that helps fight infection can drive inflammation in susceptible individuals.
Clinical Context
LL-37 is the only known cathelicidin in humans, derived from the precursor protein hCAP-18. It's a 37-amino-acid antimicrobial peptide secreted by neutrophils, macrophages, and epithelial cells. Beyond direct microbial killing via membrane disruption, LL-37 modulates immune response, promotes angiogenesis, and accelerates re-epithelialization. Therapeutic interest spans diabetic ulcers, chronic biofilm infections, and as an adjunct to antibiotic-resistant pathogen treatment. It remains a research compound — there is no FDA-approved formulation.
Common Mistakes to Avoid
Using it for general wellness
LL-37 is not a longevity peptide. It's a targeted antimicrobial / immunomodulator. Without a specific infection or wound-healing target, you're inviting unnecessary immune activation.
Skipping autoimmune screening
If you have psoriasis, rosacea, or any autoimmune condition, LL-37 can trigger flares. Get an autoimmune panel before starting.
Continuous dosing
Most physicians cycle LL-37 in 4-6 week courses with breaks. Continuous use is poorly characterized and risks dysregulating innate immunity.
Important Safety Information
Medical Disclaimer: The information provided about LL-37 is for educational purposes only and is not intended as medical advice. Always consult with a qualified healthcare provider before starting any new supplement or peptide protocol.
Research Status: While LL-37 has shown promising results in research studies, many peptides are still being studied and may not be approved by regulatory bodies like the FDA for specific uses. The research cited represents ongoing scientific investigation.
Individual Variation: Responses to peptides vary significantly between individuals. What works for one person may not work for another. Side effects, while generally mild, can occur and should be monitored closely.
Quality & Sourcing: If you choose to use peptides, ensure you obtain them from reputable, tested sources. Peptide quality, purity, and proper storage are critical for safety and efficacy.
Legal Considerations: Peptide regulations vary by country and jurisdiction. Some peptides may require a prescription or may have restrictions on their use. Research the laws in your area before obtaining or using peptides.