LL-37 dosage and protocol
Last reviewed Oct 20, 2026. Editorial policy
US regulatory status: Off Category 2, review pending
Antimicrobial, antiviral peptide that serves as alternative to antibiotics with immune-boosting properties
- Vial size: 5 mg
- Reconstitution: 3 mL bacteriostatic water
- Concentration: 1.67 mg/mL
- Administration: subcutaneous
Research areas
- Immunity
- Antimicrobial
- Wound Healing
- Infection Fighting
Quick start
- Reconstitute: Add 3 mL bacteriostatic water to the 5 mg vial for about 1.67 mg/mL
- Typical dose: 50 mcg daily in week 1, adding 50 mcg each week to about 400 mcg
- Easy measuring: At 1.67 mg/mL, 1 unit is about 16.7 mcg on a U-100 syringe, so 50 mcg is 3 units and 400 mcg is 24 units
- Storage: Freeze unreconstituted at -20°C; refrigerate after mixing and use within 4 weeks
Dosing protocol
| Phase | Dose | Frequency | Volume |
|---|---|---|---|
| Week 1 | 50 mcg | Once daily (SC) | 0.03 mL (3 units) |
| Week 2 | 100 mcg | Once daily (SC) | 0.06 mL (6 units) |
| Week 3 | 150 mcg | Once daily (SC) | 0.09 mL (9 units) |
| Week 4 | 200 mcg | Once daily (SC) | 0.12 mL (12 units) |
| Weeks 5–8 | 250–400 mcg | Once daily (SC) | 0.15–0.24 mL (15–24 units) |
How it works
LL-37 is the only human member of the cathelicidin family of host-defense peptides. It is a 37-amino-acid, positively charged, amphipathic peptide cleaved from the precursor hCAP-18 and released by neutrophils and epithelial cells. Its direct antimicrobial action comes from binding negatively charged bacterial membranes and disrupting them; it also shows activity against some enveloped viruses and fungi and can interfere with biofilm formation in laboratory studies. Beyond killing microbes, LL-37 is a signaling molecule. It interacts with receptors such as FPR2, P2X7 and EGFR, recruiting immune cells, modulating cytokine release, neutralizing bacterial endotoxin, and promoting keratinocyte migration and new blood vessel formation, which links it to wound healing. Vitamin D drives its expression, which is part of why vitamin D status is studied in relation to infection risk. Evidence is mainly from cell and animal studies. A small human trial applied LL-37 topically to chronic venous leg ulcers with signals of improved healing, but there are no established clinical trials supporting systemic injection for infection. LL-37 is also double-edged: elevated levels are implicated in inflammatory skin diseases such as psoriasis and rosacea, and it can be toxic to human cells at higher concentrations.
Units chart for a 5 mg vial
| Water added | Strength | 1 unit = | 50 mcg | 100 mcg | 150 mcg | 200 mcg |
|---|---|---|---|---|---|---|
| 1 mL | 5 mg/mL | 50 mcg | 1 units | 2 units | 3 units | 4 units |
| 2 mL | 2.5 mg/mL | 25 mcg | 2 units | 4 units | 6 units | 8 units |
| 3 mL | 1.67 mg/mL | 16.7 mcg | 3 units | 6 units | 9 units | 12 units |
Units on a U-100 insulin syringe (100 units = 1 mL).
Pages for each vial size and water volume
Reconstitution steps
- Draw 3.0 mL bacteriostatic water with a sterile syringe
- Inject slowly down the vial wall; avoid foaming
- Gently swirl/roll until dissolved (do not shake)
- Label and refrigerate at 2–8°C, protected from light; use within 4 weeks
Storage
Evidence: Common practice. What vendors and users usually do. No published stability testing supports a specific number.
- Powder or unopened: Sealed powder: freezer (about −20 °C) for long-term storage, refrigerator for weeks. Let the vial reach room temperature before opening.
- Mixed or in use: Refrigerator, 2–8 °C. Do not freeze and thaw repeatedly.
- Use within: no tested number
- Light: Keep it in the box or another dark container.
Most reconstituted peptides are kept in the refrigerator (2–8 °C) and used within about 28 days. That is a convention, not tested data: the 28 days comes from the USP <797> limit for opened multiple-dose containers, which is about sterility, not about whether the peptide stays intact.
Sources: Crestigen: Peptide storage and handling guide; USP General Chapter <797> Pharmaceutical Compounding: Sterile Preparations
Store unreconstituted at -20°C. Refrigerate after mixing at 2-8°C
Important notes
- Broad-spectrum defense against bacteria and viruses
- Best taken during serious infections
- 4-6 week cycles with evaluation of response
- Can cause increased inflammation if overdosed
- Risk of autoimmune activation at high levels
- May damage sperm membranes
- Work with doctor - high risk if misused
- Start with TA-1 or TB-4 for safer immune support
Supplies
- Bacteriostatic water (5mL)
- Insulin syringes
- Alcohol swabs