LL-37
L-L thirty-seven
Your body's natural antimicrobial peptide — part of your innate immune defense against bacteria, viruses, and fungi.
Also known as: Cathelicidin, Human Cathelicidin Antimicrobial Peptide
Last reviewed: April 2026
What It Does
LL-37 is a 37-amino-acid peptide your body produces as a first line of defense against pathogens. It directly kills bacteria by disrupting their cell membranes, while also modulating your immune response. Research interest focuses on its potential for chronic infections and immune dysregulation.
Why People Take It
How It's Administered
Subcutaneous Injection
Injection
Frequency
As directed by provider
Pain Level
●○○ Minimal
Self-Administered
Yes — at home
Typical Range
100mcg – 200mcg
What To Expect
Week 1–2
Immune activation begins.
Month 1+
Potential improvement in chronic infection symptoms.
Side Effects
Overall: Mild
Common (1–10%)
Injection site reaction
Redness and warmth.
Uncommon (0.1–1%)
Flu-like symptoms
Brief immune activation response.
Who Should NOT Take This
• Autoimmune conditions (may exacerbate)
• Pregnancy
Drug Interactions
• Immunosuppressants — may counteract
• Antibiotics — may be synergistic
Pregnancy: Not studied in supplemental form. Avoid.
Clinical Details
Compare With Similar Peptides
LL-37 directly kills pathogens and modulates innate immunity. Thymosin Alpha-1 modulates adaptive (T-cell) immunity. Different branches of the immune system.
Open Full Comparison Tool →Frequently Asked Questions
This compound is in early research stages. We do not currently offer it.
Looking for something similar? See what we offer for Immune.
This compound is in early research stages. It has not been FDA-approved and may not be available through compounding pharmacies. The information below is for educational purposes only. Do not attempt to self-administer research compounds.