What Is LL-37? Benefits, Research & Safety
The only human cathelicidin antimicrobial peptide, with broad-spectrum antimicrobial activity and important immunomodulatory functions.
UK summary: Not a licensed UK medicine. Endogenous antimicrobial peptide investigated for chronic infections, wound healing, and inflammation. Substantial preclinical literature; human therapeutic use is essentially absent.
Quick Facts
Overview
LL-37 — evidence and risk at a glance
Twenty standard modules scored against the Peptide Authority evidence grading methodology. Missing modules indicate the field has not yet been characterised editorially — treat absences as uncertainty rather than reassurance.
01Evidence snapshot
Not a licensed UK medicine. Endogenous antimicrobial peptide investigated for chronic infections, wound healing, and inflammation. Substantial preclinical literature; human therapeutic use is essentially absent.
02Human evidence grade
03Preclinical evidence grade
04Regulatory status
- UK: Not licensed for human use. Research compound only.
- EU: Not approved for therapeutic use.
- Notes: LL-37 is a research compound with no regulatory approvals. Therapeutic development continues but the peptide's complexity presents challenges.
05Approved medical uses
None in the UK or EU as a finished medicine. (Or: not yet documented; treat as absence rather than approval.)
06Unapproved / promotional claims
- Treats antibiotic-resistant infections.
- Cures chronic Lyme or biofilm-based infections.
- Heals wounds faster than standard NHS care.
- Safe and effective long-term antimicrobial therapy.
07Common internet claims
- Marketed by 'functional medicine' clinics for chronic Lyme / biofilm infections.
- Sold by online retailers as a research-only antimicrobial peptide.
- Promoted as the natural answer to antibiotic resistance.
08Claim vs evidence
| Claim | Evidence | Human evidence? | Regulatory concern | Safer wording |
|---|---|---|---|---|
| “Treats chronic infections antibiotics can't” | D | No | High | Mechanistic and animal-model evidence; no human RCT support for antibiotic-resistant infection treatment. |
| “Heals wounds faster than standard care” | D | No | High | Animal wound-healing data exist; no human RCT vs standard care. |
09Safety uncertainty score
Limited human safety data; meaningful uncertainty about rare or long-term effects.
10Known adverse signals
- Pro-inflammatory and immunomodulatory effects — can amplify inflammation.
- Theoretical risk in autoimmune disease.
- Injection-site reactions.
- Unknown effects of sustained exogenous cathelicidin exposure.
11Drug-interaction uncertainty
Interaction picture sparse; meaningful uncertainty when combined with other medicines.
12Anti-doping status
13UK legal position
Not licensed for human use. Research compound only.
14EU legal position
Not approved for therapeutic use.
15What this page cannot tell you
- Whether a UK-purchased vial contains LL-37 at the labelled concentration.
- Whether the antimicrobial mechanism translates from petri dish to human infection.
- Long-term effects of sustained antimicrobial peptide elevation.
- Whether it interacts with prescribed antibiotics or immunosuppressants.
16Last reviewed
17Citation quality score
18Research gaps
- No registered Phase 2 or 3 trials in humans for any indication.
- Antimicrobial in vitro activity does not equal clinical effectiveness.
- Long-term safety entirely unstudied.
- Combination with conventional antibiotics uncharacterised.
19Safer alternatives / established care pathways
- GP and infectious-diseases referral for suspected chronic infection.
- NHS antimicrobial-stewardship pathway for resistant infections.
- NHS wound clinic for non-healing wounds — substantial evidence-based options exist.
20Doctor discussion prompts
Questions to ask a qualified clinician
These are starter questions you can adapt for a GP, specialist, pharmacist, or anti-doping advisor. The aim is to help you have a better-informed conversation — not to replace one.
- Is LL-37 a licensed UK medicine?
- What licensed treatments exist for the infection or wound concern I have?
- Why is mechanistic plausibility not the same as proven benefit here?
Discovery & History
Mechanism of Action
Researched Benefits
Based on preclinical and clinical research findings:
- 1Broad-spectrum antimicrobial activity against bacteria, viruses, and fungi
- 2LPS neutralisation reducing sepsis-related inflammation
- 3Wound healing promotion
- 4Biofilm disruption
- 5Immunomodulatory effects
- 6Potential applications in infection control
Claim vs Evidence
How popular claims about LL-37 stack up against the current research, graded using our public evidence grading methodology.
| Claim | Evidence | Human evidence? | Regulatory concern | Safer wording |
|---|---|---|---|---|
| “Treats chronic infections antibiotics can't” | D | No | High | Mechanistic and animal-model evidence; no human RCT support for antibiotic-resistant infection treatment. |
| “Heals wounds faster than standard care” | D | No | High | Animal wound-healing data exist; no human RCT vs standard care. |
Theoretical Dosing & Protocols
| Theoretical Dosage | Not established; highly variable in research |
| Frequency | Variable depending on application |
| Duration | Variable |
| Notes | LL-37 is not approved for therapeutic use. Research applications vary widely depending on the condition being studied. The peptide's complex biology makes dosing and application challenging. |
Administration Routes
Routes studied in research settings (educational only):
- Topical (wound healing research)
- Injection (various research applications)
- Inhaled (respiratory research)
| Half-Life | Stability |
|---|---|
| Short; subject to proteolytic degradation in vivo | Requires careful handling; susceptible to degradation |
Safety Profile & Known Risks
Commonly Reported Side Effects
- Limited human safety data
- Potential for local irritation at high concentrations
Rare Risks & Concerns
- Pro-inflammatory effects in certain contexts
- Potential to exacerbate autoimmune inflammation
- Unknown long-term effects
Contraindications
- Psoriasis (LL-37 implicated in pathogenesis)
- Certain autoimmune conditions
- Pregnancy (no safety data)
- Active malignancy (angiogenic effects)
UK & EU Regulatory Context
🇬🇧 United Kingdom
Not licensed for human use. Research compound only.
🇪🇺 European Union
Not approved for therapeutic use.
Clinical Studies Summary
LL-37 in Wound Healing
Research investigating LL-37's effects on wound healing and tissue repair.
Antimicrobial Properties of Human Cathelicidin LL-37
Studies characterising LL-37's broad-spectrum antimicrobial activity.
Looking for LL-37?
Source research-grade LL-37 from a trusted UK supplier — third-party tested with certificate of analysis.
View at SupplierFrequently Asked Questions
Questions to ask a qualified clinician about LL-37
These are starter questions you can adapt for a GP, specialist, pharmacist, or anti-doping advisor. The aim is to help you have a better-informed conversation — not to replace one.
- Is LL-37 a licensed UK medicine?
- What licensed treatments exist for the infection or wound concern I have?
- Why is mechanistic plausibility not the same as proven benefit here?
UK regulatory & safety context
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