What is LL-37?
LL-37 is the only cathelicidin antimicrobial peptide expressed in humans, derived from cleavage of the C-terminus of hCAP18. It demonstrates broad-spectrum antimicrobial activity against bacteria (including MRSA), fungi, and viruses, and also plays critical roles in wound healing, immune modulation, and anti-tumor activity. Expressed primarily in neutrophils, epithelial cells, and skin. Research only.
Mechanism of Action
Membrane disruption of microbial cells via electrostatic interaction with anionic phospholipids; TLR4 modulation and FPRL1 (formyl peptide receptor like-1) signaling for immune modulation; promotes keratinocyte migration and angiogenesis via EGF receptor transactivation
Target: Microbial membranes, TLR4, FPRL1, EGF receptor
Research Indications
Demonstrated broad-spectrum antimicrobial properties in research
May help prevent microbial colonization of wounds
Activates innate immune responses against pathogens
Research Protocols
These are commonly discussed research protocols — not medical advice. Consult a healthcare provider before use.
| Goal | Dose | Frequency | Route |
|---|---|---|---|
| Starting Dose | Low dose | Per protocol | Varies |
| Standard Dose | Titrated | Per protocol | Varies |
Peptide & Drug Interactions
Always consult your healthcare provider before combining with other compounds. Use our Interaction Checker for reference.
How to Reconstitute & Inject
Use bacteriostatic (BAC) water only. Avoid saline — may cause precipitation. Refrigerate and use within 28 days.
- 1
Remove LL-37 vial from refrigeration and allow to reach room temperature (15–20 minutes)
- 2
Clean vial top with alcohol swab and allow to air dry completely
- 3
Using a sterile syringe, draw the calculated volume of bacteriostatic water (BAC water)
- 4
Inject BAC water slowly down the side of the vial — do not aim directly at the powder
- 5
Gently swirl in circular motions — DO NOT shake vigorously as this degrades the peptide
- 6
Allow 2–3 minutes for full dissolution — solution should be clear and colorless
- 7
Draw calculated dose into an insulin syringe for subcutaneous injection
- 8
Inject into abdomen, thigh, or upper arm. Rotate injection sites to prevent lipodystrophy
- 9
Store reconstituted solution refrigerated (2–8°C) and use within 28 days
What to Expect
Week 1–2
Initial effects and adaptation period. Monitor for any adverse reactions.
Week 2–4
Primary effects begin to manifest. Adjust dosing as recommended by your provider.
Week 4–8
Main therapeutic effects should be established. Assess progress with your provider.
Week 8+
Evaluate results and determine continuation, cycling, or dose adjustments.
Side Effects & Safety
- Injection site reactions (redness, bruising, mild pain)
- Potential for allergic reaction — discontinue if rash or hives occur
- Individual reactions vary — start at the lowest dose and monitor carefully
- Consult your healthcare provider before use and report any unusual symptoms
FDA Status & Regulatory Info
LL-37 is the only cathelicidin antimicrobial peptide expressed in humans, derived from cleavage of the C-terminus of hCAP18. It demonstrates broad-spectrum antimicrobial activity against bacteria (including MRSA), fungi, and viruses, and also plays critical roles in wound healing, immune modulation, and anti-tumor activity. Expressed primarily in neutrophils, epithelial cells, and skin. Research only.
Frequently Asked Questions
Research References
External links for education only. We do not control third-party content.
Community-reported data
The information below reflects self-reported experiences from PeptIQ app users. It is not clinical evidence and should not replace professional medical advice.
Community Intelligence
What 6 users report
Positive 100% · Neutral 0% · Negative 0%
Most reported benefits
Dose distribution
Median: 100–200 mcg · Most common: 100–200 mcg
Commonly stacked with
Share Your Experience
Rate LL-37 in the PeptIQ app and help the community make informed decisions.
Research purposes only
This page is for educational reference. It is not medical or legal advice. Consult the FDA and a licensed healthcare professional for current regulations and individualized guidance.