LL-37 vs Rusfertide
Overview
LL-37 is primarily a immune support peptide, while Rusfertide is used for weight management & metabolic.
This page compares LL-37 and Rusfertide across their primary use, typical dosing, reported benefits and side effects, and U.S. regulatory status. For the full monograph on either compound — mechanism of action, clinical research, and references — follow the article links.
Side-by-side comparison
| LL-37 | Rusfertide | |
|---|---|---|
| Category | Immune Support | Weight Management & Metabolic |
| Regulatory status (US) | Compounding (Rx) — Apr 2026 | FDA approved |
| Typical dosage | 2-5 mg | 19-108 mg |
| Frequency | twice weekly | once weekly, subcutaneous |
| Reported benefits | Antimicrobial activity, immune modulation, wound healing, anti-inflammatory | In the Phase 3 VERIFY trial, adding rusfertide to standard-of-care therapy allowed 76.9% of participants to achieve hematocrit control without phlebotomy during weeks 20-32, compared with 32.9% on placebo plus standard of care. Reported benefits are specific to polycythemia vera erythrocytosis management and have not been studied for other conditions. |
| Reported side effects | Generally safe, minimal side effects | Injection-site reactions (56%) and anemia (16%) were the most common adverse events in clinical trials; labeled warnings include thrombocytosis and embryo-fetal toxicity. |
Key differences
Primary use. LL-37 is categorised under Immune Support, while Rusfertide falls under Weight Management & Metabolic. Their differing categories mean they are usually chosen for different goals rather than as direct substitutes.
Regulatory status. LL-37: not FDA-approved; compounding permitted with a prescription as of April 2026. Rusfertide: FDA-approved.
Dosing. LL-37 is typically dosed at 2-5 mg (twice weekly). Rusfertide is typically dosed at 19-108 mg (once weekly, subcutaneous).
Can you stack them?
Some protocols combine peptides, but stacking LL-37 and Rusfertide has not been validated for safety or efficacy in controlled trials. Combining compounds can change their effects and risks. Nothing here is medical advice — consult a qualified healthcare provider before starting or combining any protocol.
Frequently asked questions
- What is the difference between LL-37 and Rusfertide?
- LL-37 is primarily a immune support peptide, while Rusfertide is used for weight management & metabolic. LL-37 is not FDA-approved; compounding permitted with a prescription (as of April 2026), whereas Rusfertide is FDA-approved for one or more indications.
- What is LL-37 used for?
- Antimicrobial defense peptide.
- What is Rusfertide used for?
- A once-weekly injectable hepcidin-mimetic peptide FDA-approved to treat erythrocytosis in adults with polycythemia vera.
- Can you take LL-37 and Rusfertide together?
- Some users combine peptides within a single protocol, but stacking LL-37 and Rusfertide has not been established as safe or effective in controlled trials. Neither this comparison nor PeptideSciences101 is medical advice — consult a qualified healthcare provider before combining any compounds.
- Is LL-37 or Rusfertide FDA-approved?
- LL-37 is not FDA-approved; compounding permitted with a prescription (as of April 2026). Rusfertide is FDA-approved for one or more indications.
Read the full articles
- LL-37 — full monograph: mechanism, research, dosing & references
- Rusfertide — full monograph: mechanism, research, dosing & references