LL-37 5mg · Human Cathelicidin Antimicrobial Peptide · 98.6% Purity

What is LL-37?

LL-37 is the only human cathelicidin antimicrobial peptide — a 37-amino-acid host-defense peptide expressed by neutrophils, mast cells, and keratinocytes. It provides broad-spectrum bactericidal activity (gram-positive and gram-negative), antifungal action, and crucially disrupts bacterial biofilms that conventional antibiotics cannot penetrate — making it a central tool in advanced immune research.

What is LL-37 used for?

Most-studied applications: chronic biofilm infections (sinus, urinary, skin), atopic dermatitis research, wound healing acceleration, and immune modulation in deficiency states. Stacked with Thymosin Alpha-1 for compound immune protocols and with KPV for combined antimicrobial + anti-inflammatory research. Sometimes paired with BPC-157 for gut-inflammation research.

How does it work?

37-amino-acid cathelicidin antimicrobial peptide; broad-spectrum bactericidal activity, biofilm disruption, immune-modulation, and wound-healing acceleration. Read our complete research hub for the full literature review, or jump to our best peptides for immune article for comparator molecules.

Why this listing?

LL-37 levels are reduced in atopic dermatitis and certain chronic infections, providing the rationale for supplementation research. Lumen Labs' batch LL3-2604-A tested 98.6% pure by HPLC. Cold-chain shipping mandatory.

How Peptide.best sources and verifies LL-37

Every LL-37 listing on Peptide.best comes from a verified vendor that has passed our onboarding audit — GMP-licensed manufacturing facility, documented chain of custody, third-party Janoshik Analytical testing on every batch, and a published Certificate of Analysis. Lumen Labs (the seller on this listing) currently maintains a 4.9-star average across all their products. Compare the five live offers on the right side of this page — Peptide.best forces vendors to compete on price and purity for the same SKU, so you always see the best current deal at the top, with the COA-verified purity, shipping speed, and seller rating side-by-side. Looking for alternatives in the same immune space? Thymosin Alpha-1 and the other peptides listed under our Immune category are the most commonly compared alternatives.

Commonly stacked with

Thymosin Alpha-1 · KPV · BPC-157 · GHK-Cu. See the peptide stacks page for full protocol writeups.

Compliance notice

LL-37 has not been evaluated by the FDA for any indication. All statements on this page are based on published research and are not medical claims. Some products may be sold for research purposes only as marked. Consult a licensed healthcare provider before use. See our full disclaimer.

Research literature

LL-37 has been the subject of growing peer-reviewed and preclinical research across the immune domain. The current PubMed index returns several hundred citations spanning mechanism, dose-response, and adverse-event reporting.

Key references commonly cited in LL-37 research:

• Mechanism papers covering 37-amino-acid cathelicidin antimicrobial peptide; broad-spectrum bactericidal activity, biofilm disruption, immune-modulation, and wound-healing acceleration.
• Dose-response work in rodent models (most studied species)
• Comparator-molecule trials vs. Thymosin Alpha-1 and other peptides in the same class
• Safety / pharmacovigilance datasets where available

For a full reference list, see the Peptide.best Research Hub or the dedicated Immune pillar article.

Standard research dosing

Standard research protocol: 100–500 mcg subcutaneous, daily, 14–28 day cycles. Topical formulations also documented for skin research.

Reconstitution

This product ships as lyophilized powder. Reconstitute with Bacteriostatic water (2mL) for stable refrigerated storage. Once reconstituted, use within 30 days; keep at 2–8°C.

Protocol notes

For full protocols and stacking guidance, see our peptide dosing guides. Always start at the low end of the published range and titrate based on individual response. Half-life (~30 min systemic) determines dosing frequency.

Reported side effects

Most-reported: transient injection-site reaction, mild flu-like symptoms in first 2–3 doses (immune activation). Possible histamine release at high doses.

Contraindications

Do not use during pregnancy or lactation. Do not combine with other peptides without reviewing pharmacology. Consult a licensed healthcare provider before beginning any peptide research protocol. Discontinue immediately if any adverse reaction occurs and contact your provider.

Drug interactions

Limited interaction data exists for most research peptides. Be especially cautious when combining with prescription medications affecting the same physiological pathway as LL-37 (immune pathway).

Certificate of Analysis

Every batch of LL-37 sold on Peptide.best ships with a third-party Certificate of Analysis (COA) from Janoshik Analytical — the most-cited independent peptide testing lab in the research community.

Current batch testing summary

• Batch ID: LL3-2604-A
• Test date: 04/14/2026
• Peptide content (HPLC): 98.6%
• Mass-spec identity: Confirmed (target mass match)
• Endotoxin (LAL): Below detection limit
• Residual solvents: Within USP <467> limits

Download full COA PDF

For our overall testing process and chain-of-custody details, see Trust & Safety.

Q: Is LL-37 legal to purchase?

A: LL-37 is sold on Peptide.best for research purposes where applicable. Legal status varies by jurisdiction. See our disclaimer for full details.

Q: How long until I see effects?

A: Timing depends on protocol, dose, and individual response. Most users report observable changes within 2–6 weeks of consistent dosing per the standard research protocols. See the Dosing & Protocol tab.

Q: Can I stack LL-37 with other peptides?

A: Yes — see commonly stacked peptides in the Overview tab, or browse our peptide stacks page for full protocol writeups.

Q: Why is the price lower than pharmacy retail or other research sites?

A: Peptide.best aggregates verified vendors and forces them to compete in a single checkout. Vendors save on customer-acquisition cost; the savings pass to you. Every batch is still 3rd-party COA tested.

About Lumen Labs

Lumen Labs is one of the six verified vendor partners on Peptide.best. They maintain a 4.9-star average rating across all products and submit every batch to third-party HPLC analysis before it ships.

All Lumen Labs products on Peptide.best ship from a GMP-licensed contract manufacturing facility and are tested by Janoshik Analytical. Cold-chain shipping is included on temperature-sensitive products.