MOD-GRF (1-29) vs Sermorelin: the honest comparison
Mod-GRF 1-29 is the stabilized modern version; Sermorelin is the unmodified native GHRH(1-29). Mod-GRF has a slightly longer effective duration due to structural stabilization (tetrasubstitution) and is more resistant to enzymatic degradation — but the practical difference in dosing cadence is small. Sermorelin has the clinical track record; Mod-GRF is the research-market standard.
Side-by-side facts
| MOD-GRF (1-29) | Sermorelin | |
|---|---|---|
| Class | GHRH analog (short-acting) | Growth hormone-releasing hormone analog (GHRH 1-29) |
| Half-life | Approximately 30 minutes | Approximately 10–20 minutes |
| Typical dose | 100 mcg per injection, 1–3x daily (often pre-bed and/or post-workout) | 100–500 mcg per injection, typically at bedtime 5 days per week |
| Category | Growth hormone axis | GH secretagogue (GHRH) |
| FDA status | Not FDA approved. Research use only in the US. | Previously FDA approved for pediatric GH deficiency (withdrawn in 2008 for commercial reasons, not safety). Widely compounded. |
| Storage | Lyophilized: refrigerated. | Lyophilized refrigerated. |
What they have in common
Both are GHRH(1-29) peptides that bind pituitary GHRH receptors and produce short GH pulses. Both have half-lives on the order of tens of minutes and are typically injected daily (often pre-bed) and paired with a GHRP.
When to pick MOD-GRF (1-29)
Pick Mod-GRF 1-29 when you want the research-peptide default with structural stabilization for better in-vivo persistence. Tetrasubstitution (the "modifications" in "Mod-GRF") slows enzymatic cleavage compared to native GHRH. Typical dose: 100 mcg per injection, 1–3× daily.
When to pick Sermorelin
Pick Sermorelin when you want the compound with the deepest clinical history — FDA-approved historically as Geref for pediatric GH deficiency and widely used in adult anti-aging clinics. Unmodified GHRH(1-29), shorter half-life (~10–15 minutes), cleanest physiological pulse.
Can you stack them?
No — both are GHRH(1-29) analogs acting on the same receptor. Pick one as your GHRH input and pair with a GHRP.
The two compounds
MOD-GRF (1-29)
MOD-GRF (1-29), also sold as CJC-1295 without DAC, is a stabilized analog of the first 29 amino acids of human GHRH. Commonly supplied as…
Sermorelin
Sermorelin is a truncated 29-amino-acid analog of endogenous growth-hormone-releasing hormone (GHRH). It stimulates the pituitary to rele…
Track either compound on iPhone
Peptide Protocol schedules doses, calculates reconstitution, and logs side effects for both — on iPhone, free to download.
See the app →Frequently asked questions
What is the main difference between MOD-GRF (1-29) and Sermorelin?
Modification. Mod-GRF 1-29 is the stabilized analog with amino acid substitutions at positions 2, 8, 15, and 27. Sermorelin is the unmodified native sequence. Practical effect: Mod-GRF persists slightly longer in circulation but produces essentially the same GH-pulse profile.
Can you stack MOD-GRF (1-29) and Sermorelin?
No — both are GHRH(1-29) analogs acting on the same receptor. Pick one as your GHRH input and pair with a GHRP.
Which is better, MOD-GRF (1-29) or Sermorelin?
Mod-GRF 1-29 is the stabilized modern version; Sermorelin is the unmodified native GHRH(1-29). Mod-GRF has a slightly longer effective duration due to structural stabilization (tetrasubstitution) and is more resistant to enzymatic degradation — but the practical difference in dosing cadence is small. Sermorelin has the clinical track record; Mod-GRF is the research-market standard.
When should I pick MOD-GRF (1-29)?
Pick Mod-GRF 1-29 when you want the research-peptide default with structural stabilization for better in-vivo persistence. Tetrasubstitution (the "modifications" in "Mod-GRF") slows enzymatic cleavage compared to native GHRH. Typical dose: 100 mcg per injection, 1–3× daily.
When should I pick Sermorelin?
Pick Sermorelin when you want the compound with the deepest clinical history — FDA-approved historically as Geref for pediatric GH deficiency and widely used in adult anti-aging clinics. Unmodified GHRH(1-29), shorter half-life (~10–15 minutes), cleanest physiological pulse.
Are MOD-GRF (1-29) and Sermorelin FDA approved?
MOD-GRF (1-29): Not FDA approved. Research use only in the US. — Sermorelin: Previously FDA approved for pediatric GH deficiency (withdrawn in 2008 for commercial reasons, not safety). Widely compounded.
Educational use only. Peptide Protocol is an informational tool. Nothing on this page constitutes medical advice. Many peptides are prescription-only or restricted in your jurisdiction. Always consult a licensed healthcare professional before injecting any compound.