GHRP-6 vs PEG-MGF
A neutral, side-by-side comparison of two performance & growth hormone peptides — their mechanisms, dosing ranges, administration routes, side effects, and research evidence. For research and educational purposes only.
GHRP-6
GHRP-6 is a first-generation synthetic hexapeptide GH secretagogue that strongly stimulates pituitary GH release via ghrelin receptor activation. It is one of the oldest and most well-studied GHRPs, with a large body of research spanning more than three decades. GHRP-6 produces significant GH pulses but is notable for powerfully stimulating appetite — a side effect that can be beneficial for those in a caloric deficit or disadvantageous for those managing body composition.
Full profilePEG-MGF
PEG-MGF is Mechano Growth Factor (MGF) conjugated to a polyethylene glycol (PEG) polymer chain. The PEGylation dramatically extends the half-life from ~5 minutes (native MGF) to approximately 24–72 hours, allowing less frequent dosing and systemic distribution rather than purely local action. This trade-off — longer duration vs localized intensity — makes PEG-MGF a different tool than native MGF, better suited for systemic muscle recovery support and convenience-focused protocols.
Full profile| GHRP-6 | PEG-MGF | |
|---|---|---|
| Category | Performance & Growth Hormone | Performance & Growth Hormone |
| Also known as | Growth Hormone Releasing Peptide-6, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 | PEGylated Mechano Growth Factor, Polyethylene Glycol-MGF, Long-acting MGF |
| Evidence | Preclinical only | Preclinical only |
| Dosing range | 100mcg–300mcg mcg, 1–3 times daily, on an empty stomach | 100mcg–400mcg mcg, 2x weekly (Monday/Thursday or similar split) |
| Administration | Subcutaneous injection, Intramuscular injection | Subcutaneous injection (preferred for systemic distribution), Intramuscular injection |
| Key side effects | Strong increase in appetite (most common and notable), Elevated cortisol and prolactin at higher doses, Water retention / bloating, Fatigue at high doses | Hypoglycemia (less pronounced than IGF-1 DES, more than native MGF due to systemic distribution), Generalized fatigue on injection days, PEG accumulation concern with very high doses over long periods (theoretical — not established at research doses), Localized injection site swelling |
| Cited sources | 3 references | 2 references |
Key differences
- Administration: GHRP-6 — Subcutaneous injection, Intramuscular injection; PEG-MGF — Subcutaneous injection (preferred for systemic distribution), Intramuscular injection.
- Frequency: GHRP-6 is typically 1–3 times daily, on an empty stomach; PEG-MGF is 2x weekly (Monday/Thursday or similar split).
- Research depth: this profile cites 3 sources for GHRP-6 vs 2 for PEG-MGF.
How each works
GHRP-6
Human studies confirm GHRP-6 robustly elevates GH within 15–30 minutes of injection, with effects diminishing toward baseline within 2–3 hours. Chronic use increases baseline IGF-1. Research also indicates mild stimulation of cortisol and prolactin, particularly at higher doses. Animal models have shown potential cardioprotective, hepatoprotective, and muscle-sparing effects, though human equivalents are not established.
PEG-MGF
PEGylation is a validated pharmaceutical strategy for extending peptide half-life (used in Pegasys/interferon, Somavert/pegvisomant, and others). The PEG chain shields the MGF peptide from proteolytic degradation and slows renal clearance. Research in rodent models confirms PEG-MGF preserves the biological activity of native MGF (satellite cell activation, muscle repair) with extended duration. Unlike native MGF which requires precise post-workout injection timing, PEG-MGF can be injected on a scheduled basis and still achieves systemic muscle-wide satellite cell effects.
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.