Mod GRF 1-29
Short-acting, pulsatile GHRH analog - the GHRH half of the classic Ipamorelin stack.
Human & AnimalSyntheticInjectablePulsatile
Key facts
Common routesSubcutaneous
Half-life~30 minutes
Typical range100 mcg/dose, 1-3x daily
Summary
Mod GRF 1-29 (tetrasubstituted GRF 1-29) is a synthetic, stable version of the first 29 amino acids of native GHRH. The modifications make the peptide injection-viable but keep its half-life around 30 minutes - short enough to fire a single clean GH pulse instead of producing the sustained GH bleed of CJC-1295 (DAC).
In practice, Mod GRF is almost always the GHRH half of a stack with a GHS like Ipamorelin. 100 mcg Mod GRF + 100 mcg Ipamorelin, 1-3× daily, is the community standard for a clean GH pulse: bigger than either component alone, without the side-effect profile of a non-pulsatile release.
Mechanism notes
GHRH receptor agonism
Binds pituitary GHRH receptors and triggers a single GH pulse. Same pharmacological target as CJC-1295 (DAC), minus the Drug Affinity Complex - so no albumin binding and no multi-day half-life.
Pulsatile release
A ~30-minute half-life means one clean, time-bounded pulse instead of a constant bleed. That's the reason Mod GRF produces less water retention, less insulin resistance, and no carpal tunnel symptoms. It mimics natural nighttime GH physiology instead of overwriting it.
Synergy with GHRPs
A GHRH (Mod GRF) and a GHS (Ipamorelin or GHRP-2/6) together create a GH pulse larger than the sum of their individual pulses. That's the pharmacological basis for the “no-side-effect stack”: 100 mcg Mod GRF + 100 mcg Ipamorelin, injected fasted.
Dosing patterns
Standard stack (Mod GRF + Ipamorelin)
100 mcg Mod GRF 1-29 + 100 mcg Ipamorelin, subcutaneous, fasted, 1-3× daily (AM, pre-workout, pre-bed). Wait 30-60 min after injection before eating. This is the bread-and-butter GH protocol in the community - not magic, but consistent effect with minimal side effects.
Mod GRF solo (anti-aging)
100 mcg pre-bed, once daily. Amplifies the natural nighttime GH pulse and subjectively improves sleep quality and skin, without downregulating natural production. The effect is subtle - for dramatic outcomes, stack with a GHS.
Evidence snapshot
The underlying GHRH biology has been characterized since the 1980s (Lance et al., 1984). Tetrasubstituted GRF 1-29 is a stabilized version of the native human peptide - no dedicated large RCT, but the physiology is well understood. Community usage is uniformly positive and consistent with expected GH/IGF-1 biology.
Foundational research (Lance 1984)
Describes the tetrasubstituted GHRH(1-29) analogs - stable enough for injection, short enough to stay pulsatile.
Community usage
High consensus across HRT clinics and bodybuilding communities; treated as the gold-standard GHRH for daily use.
Safety considerations
The side-effect profile is the cleanest of any GHRH analog: brief head rush/flush after injection, occasional mild headache, injection-site reaction. No meaningful water retention, no cortisol or prolactin impact. The main risks are practical: high injection frequency and mislabeling in the market.
Key cautions
- Insulin and glucose blunt the GH pulse - dose on an empty stomach (~2 hours post-meal)
- Often mislabeled as "CJC-1295 without DAC" at point of sale - verify it's actually tetrasubstituted GRF 1-29
- Multi-daily injections are required to match physiological GH pulses; skipping pulses undermines the protocol