LL-37
Last reviewed May 27, 2026
Also known as: Cathelicidin, CAP-18, hCAP-18
Quick Answer
LL-37 is a antimicrobial peptide research compound (not FDA-approved for human use) studied for broad-spectrum antimicrobial. LL-37 is the only human antimicrobial cathelicidin peptide studied for directly killing bacteria, viruses, and fungi while also promoting wound healing and immune system activation. Research dose: 100–100 mcg 7x/wk. Half-life: 4 hours. Available from COA-verified vendors with code PEPTIDEX for up to 20% off.
Where to Source
Ranked by $/mg1Bio Longevity Labs Best $/mg
$80.72
$94.97Save $14.25
5mg vial
$18.99/mg
99%+ purityTested May 2026
Use code for 15% off:
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Rankings independent · Research use only
The only human cathelicidin antimicrobial peptide. LL-37 is a 37-amino acid cationic peptide that directly disrupts microbial membranes (bacteria, viruses, fungi) and neutralizes bacterial endotoxins
Where to Buy LL-37
COA-verified vendors · Use code PEPTIDEX for up to 20% off
* Prices for research peptide acquisition. Not therapeutic products.
| Vendor | Purity | List Price | With PEPTIDEX | Code | Shop |
|---|---|---|---|---|---|
Bio Longevity LabsTriple-Tested | 99%+ | $94.975 mg | $80.72Save 15% | PEPTIDEX | * Research vendor — verify your regional regulations before purchase. Shop |
Bio Longevity LabsTriple-Tested
$94.97 · 5 mg$80.72−15%
Use code PEPTIDEX for 15% off at Bio Longevity Labs.
* Research vendor — verify your regional regulations before purchase.
Shop at Bio Longevity Labs§ Mechanism of Action
The only human cathelicidin antimicrobial peptide. LL-37 is a 37-amino acid cationic peptide that directly disrupts microbial membranes (bacteria, viruses, fungi) and neutralizes bacterial endotoxins (LPS). Beyond direct antimicrobial action, LL-37 modulates innate immunity by chemoattracting neutrophils, monocytes, and T-cells to infection sites. Promotes wound healing via EGFR-mediated keratinocyte migration and angiogenesis. Demonstrates potent anti-biofilm properties against resistant organisms.
§ Primary Benefits
- 1Broad-spectrum antimicrobial
- 2anti-biofilm
- 3wound healing
- 4immune modulation
- 5anti-inflammatory
§ Clinical Evidence
LL-37 broad-spectrum antimicrobial and immunomodulatory effects
Comprehensive review of LL-37's dual antimicrobial and immunomodulatory functions, including membrane disruption, chemotaxis, cytokine regulation, and wound healing promotion.
ModerateLL-37 anti-biofilm activity against resistant pathogens
Overhage et al.: LL-37 inhibits biofilm formation by Pseudomonas aeruginosa at sub-MIC concentrations, affecting bacterial attachment, migration, and quorum sensing.
PreclinicalLL-37 promotes wound healing via EGFR transactivation
Tokumaru et al.: LL-37 promotes wound re-epithelialization by stimulating keratinocyte migration through EGFR transactivation, providing mechanistic basis for wound-healing applications.
PreclinicalCathelicidin deficiency increases susceptibility to infection
Chromek et al.: Studies in CAMP-knockout models demonstrate that cathelicidin deficiency significantly increases susceptibility to urinary tract and skin infections, validating LL-37's critical role in host defense.
PreclinicalLL-37 in chronic inflammatory conditions and immune regulation
Kahlenberg et al.: Review of LL-37's role in autoimmune and chronic inflammatory conditions including psoriasis, lupus, and rosacea. LL-37 acts as a danger signal activating dendritic cells and driving type I interferon production.
ModerateVitamin D-inducible antimicrobial peptide LL-37 binds SARS-CoV-2 Spike and accessory proteins ORF7a and ORF8.
A study published in Frontiers in cellular and infection microbiology investigating the effects and mechanisms.
PreclinicalAntimicrobial peptide LL-37 and its pro-form, hCAP18, in desquamated epithelial cells of human whole saliva.
A study published in European journal of oral sciences investigating the effects and mechanisms.
ModerateInsight into the Mechanism of Interactions between the LL-37 Peptide and Model Membranes of Legionella gormanii Bacteria.
A study published in International journal of molecular sciences investigating the effects and mechanisms.
PreclinicalThe Antimicrobial Peptide LL-37 as a Predictor Biomarker for Periodontitis with the Presence and Absence of Smoking: A Case-Control Study.
A study published in BioMed research international investigating the effects and mechanisms.
AnecdotalAntimicrobial peptide CRAMP/LL-37 mediates ferroptosis resistance in cardiomyocytes by inhibiting cathepsin L.
A study published in Basic research in cardiology investigating the effects and mechanisms.
Preclinical§ Safety Profile
Endogenous human peptide with well-characterized biology. Cytotoxic to eukaryotic cells at high concentrations (>25mcg/mL). Concentration-dependent effects: low doses immunomodulatory, high doses cytotoxic. Growing research interest in CIRS/mold illness protocols. Not FDA-approved as a therapeutic.
See our evidence grading methodology for how we evaluate and grade peptide safety data.
§ Dosing Protocol
* Dosing data from published literature — not a human use recommendation.
RouteSubQ
Dose Range100–100 mcg
Frequency7x/wk
TimingAny time
Cycle Length6–6 weeks
BAC Water2.5 ml / 2mg vial
Research doses typically 50-200mcg SubQ. Start low (50mcg) to assess tolerance. Also used topically for wound applications. Practitioners in CIRS protocols often use nebulized delivery for respiratory infections.
§ Pharmacokinetics
⏱️ Half-Life: 4h
Plasma concentration over time§ Expected Outcomes
Week 1
Immune activation; some users report mild flu-like response as immune system engages
Weeks 2–4
Reduced infection symptoms; improved wound healing at treatment sites; systemic immune upregulation
Month 2–3
Sustained antimicrobial effects; biofilm disruption in chronic infections; improved mucosal barrier integrity
Long-term
Best used in targeted protocols for active infections or chronic immune challenges; not typically used indefinitely
§ Adverse Effects
| Side Effect | Incidence | Severity |
|---|---|---|
Injection site reaction (redness, swelling) Expected immune-activating response | ~15% of users | mild |
Flu-like symptoms (immune activation) Sign of immune engagement; typically resolves in 24-48 hours | ~10% of users | mild |
Mild fever | ~5% of users | mild |
Fatigue | ~8% of users | mild |
Where to Source LL-37 for Research
Finding verified, high-purity LL-37 requires rigorous COA verification. We independently evaluate vendors based on third-party HPLC testing, purity thresholds (≥98%), and batch-specific documentation.
View COA-Verified LL-37✓ Third-party tested·✓ US shipping·✓ COA on every batch
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§ Comparisons
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Cite This Page
⚠️ Educational only · Not medical advice · For research use only. Information on this page is compiled from peer-reviewed literature and is intended strictly for educational and informational purposes. Peptides discussed may be unapproved research chemicals — consult a licensed healthcare professional before considering any peptide compound. Read our full disclaimer
Affiliate disclosure: PeptiDex may earn commissions from purchases made through vendor links on this page. This does not affect our editorial ranking or vendor recommendations — we exclusively feature vendors that pass independent COA verification. See our methodology · Editorial policy
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