LL-37 vs TB-500
A neutral, side-by-side comparison of two healing & recovery peptides — their mechanisms, dosing ranges, administration routes, side effects, and research evidence. For research and educational purposes only.
LL-37
LL-37 is the only human cathelicidin — a host defense peptide produced by neutrophils, epithelial cells, and macrophages in response to infection and inflammation. It functions simultaneously as a broad-spectrum antimicrobial agent and an immune-modulatory signaling molecule. Research interest has expanded dramatically since COVID-19 studies linked low LL-37 levels to severe outcomes, and gut health research identified it as a key regulator of intestinal barrier integrity.
Full profileTB-500
TB-500 is a synthetic fragment of Thymosin Beta-4, an endogenous protein involved in cell migration, tissue repair, and inflammation regulation. It has shown significant healing properties in preclinical models across muscle, tendon, ligament, and cardiac tissue.
Full profile| LL-37 | TB-500 | |
|---|---|---|
| Category | Healing & Recovery | Healing & Recovery |
| Also known as | Cathelicidin LL-37, hCAP-18 C-terminal fragment, CRAMP (murine equivalent) | Thymosin Beta-4, Tβ4, TB500 |
| Evidence | Research-stage | Preclinical only |
| Dosing range | 100mcg–500mcg mcg, Daily or 3–5x weekly | 2mg–10mg mg, twice weekly (loading), weekly (maintenance) |
| Administration | Subcutaneous injection, Intranasal (for respiratory applications), Topical (wound care) | Subcutaneous injection, Intramuscular injection |
| Key side effects | Injection site redness and irritation (common — pro-inflammatory at injection site), Transient flu-like symptoms (immune activation), Local induration, High doses may be cytotoxic — dose-response curve is non-linear | Head rush / lightheadedness (transient), Lethargy at higher doses, Injection site discomfort, Nausea (rare) |
| Cited sources | 3 references | 2 references |
Key differences
- Evidence level differs: LL-37 is research-stage, while TB-500 is preclinical only.
- Administration: LL-37 — Subcutaneous injection, Intranasal (for respiratory applications), Topical (wound care); TB-500 — Subcutaneous injection, Intramuscular injection.
- Dosing units differ: LL-37 is dosed in mcg, TB-500 in mg — they operate at different scales.
- Frequency: LL-37 is typically Daily or 3–5x weekly; TB-500 is twice weekly (loading), weekly (maintenance).
- Research depth: this profile cites 3 sources for LL-37 vs 2 for TB-500.
How each works
LL-37
LL-37 exerts antimicrobial activity by disrupting bacterial membranes via electrostatic interaction with negatively charged lipopolysaccharide — effective against gram-positive and gram-negative bacteria, fungi, and enveloped viruses including SARS-CoV-2 in vitro. Beyond direct antimicrobial action, LL-37 modulates innate immunity through TLR4 signaling, promotes wound healing via EGFR and FPRL1 receptor activation, and has demonstrated anti-biofilm activity against P. aeruginosa and S. aureus. Vitamin D is the primary driver of endogenous LL-37 production.
TB-500
TB-500 promotes healing by upregulating actin, which drives cell migration to injury sites. Animal studies show accelerated repair of muscle tears, tendon injuries, and corneal wounds. It also demonstrates anti-inflammatory properties and has been studied for cardiac tissue repair following ischemic injury.
This comparison aggregates public research and structured profile data for informational purposes only. It is not medical advice and does not recommend either compound for human use. Consult a qualified healthcare provider before considering any peptide.