GHK (Glycine-Histidine-Lysine Tripeptide) vs LL-37
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.
GHK (Glycine-Histidine-Lysine Tripeptide)
The free tripeptide component of GHK-Cu before copper complexation. GHK naturally occurs in human plasma, saliva, and urine and promotes wound healing, collagen synthesis, and anti-inflammatory activity. While it readily chelates copper to form GHK-Cu in vivo, research distinguishes the independent effects of free GHK from the copper-complexed form on gene expression and tissue remodeling.
Full profileLL-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 profile| GHK (Glycine-Histidine-Lysine Tripeptide) | LL-37 | |
|---|---|---|
| Category | Healing & Recovery | Healing & Recovery |
| Also known as | GHK tripeptide, Gly-His-Lys, copper chelating tripeptide, GHK free tripeptide | Cathelicidin LL-37, hCAP-18 C-terminal fragment, CRAMP (murine equivalent) |
| Evidence | Research-stage | Research-stage |
| Dosing range | 0.5mg–2mg mg, Daily or every other day (topical or SC) | 100mcg–500mcg mcg, Daily or 3–5x weekly |
| Administration | Subcutaneous injection, Topical (cream/serum) | Subcutaneous injection, Intranasal (for respiratory applications), Topical (wound care) |
| Key side effects | Minimal reported side effects, Mild injection site irritation, Rare topical sensitization, No significant systemic effects at research doses | 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 |
| Cited sources | 2 references | 3 references |
Key differences
- Administration: GHK (Glycine-Histidine-Lysine Tripeptide) — Subcutaneous injection, Topical (cream/serum); LL-37 — Subcutaneous injection, Intranasal (for respiratory applications), Topical (wound care).
- Dosing units differ: GHK (Glycine-Histidine-Lysine Tripeptide) is dosed in mg, LL-37 in mcg — they operate at different scales.
- Frequency: GHK (Glycine-Histidine-Lysine Tripeptide) is typically Daily or every other day (topical or SC); LL-37 is Daily or 3–5x weekly.
- Research depth: this profile cites 2 sources for GHK (Glycine-Histidine-Lysine Tripeptide) vs 3 for LL-37.
How each works
GHK (Glycine-Histidine-Lysine Tripeptide)
Free GHK directly upregulates collagen, elastin, and laminin synthesis in fibroblasts through TGF-β pathway activation and metalloproteinase modulation. Loren Pickart's decades of research identified GHK as a potent tissue remodeling signal whose plasma concentrations decline with age. At physiologic concentrations, GHK resets approximately 31% of dysregulated gene expression associated with aging back toward a younger phenotype.
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.
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.