Head-to-head comparison
| Property | GHRP-2 | GHRP-6 |
|---|---|---|
| Category | Muscle & Growth | Muscle & Growth |
| Legal Status | Reclassification Pending | Reclassification Pending |
| Primary Route | subcutaneous | subcutaneous |
| Half-life | ~15 minutes (plasma) | ~15–20 minutes (plasma) |
| Mol. Weight | 817.97 Da | 872.45 Da |
| Side Effects | Mild increased appetite, Transient cortisol elevation, Transient prolactin elevation | Intense acute hunger / appetite surge, Cortisol elevation (transient), Prolactin elevation (transient) |
Key differences
- GH release potency: GHRP-2 is considered the more potent GH releaser of the two, producing higher peak GH levels per dose.
- Appetite stimulation: GHRP-6 produces significantly stronger appetite stimulation (via ghrelin pathway activation); GHRP-2 has moderate appetite effects that are less intense than GHRP-6.
- Cortisol/prolactin: GHRP-2 has a moderate effect on cortisol and prolactin at higher doses; GHRP-6 also raises cortisol and prolactin, with GHRP-6 having somewhat greater cortisol impact.
- Clinical data: Both have published human studies. GHRP-2 has been more extensively studied in clinical settings for GH deficiency diagnostics.
- Typical dosing: Both are commonly dosed at 100–300 mcg subcutaneously, 2–3 times daily, often paired with a GHRH analog.
- Use case: GHRP-6 is sometimes preferred when appetite stimulation is desired (e.g., underweight individuals); GHRP-2 is preferred when cleaner GH stimulation with less hunger is the goal.
- Desensitization: Both can cause some receptor desensitization with prolonged use, though less pronounced than hexarelin.
The verdict
GHRP-2 is generally the preferred choice for those seeking potent GH stimulation with less appetite stimulation. GHRP-6 is preferred when appetite increase is a desired effect (such as in bulking or recovery from illness). Both are older GH secretagogues that have been largely superseded by ipamorelin (for selectivity) and CJC-1295 (for convenience), but they remain available and well-characterized from decades of research.
Frequently asked questions
GHRP-2 is considered the more potent GH releaser, producing higher peak GH levels. GHRP-6 is notable for its very strong appetite stimulation, which can be an advantage or disadvantage depending on the protocol goal.
Yes, GHRP-6 is well known for causing intense hunger within 20–30 minutes of injection. This is a direct ghrelin pathway effect. GHRP-2 also increases appetite but to a lesser degree. Ipamorelin has the least appetite effect among ghrelin-pathway peptides.
Both act on the ghrelin receptor, so combining them provides additive but potentially redundant stimulation. A more effective strategy is combining one GHRP (GHRP-2 or GHRP-6) with a GHRH analog (like CJC-1295 or sermorelin) for synergistic GH release through two different receptor pathways.
Both remain available as research compounds, but they have been largely superseded in popularity by ipamorelin (cleaner selectivity) and MK-677 (oral convenience). GHRP-2 is still used in clinical settings as a GH provocation test for diagnosing GH deficiency.
Both can elevate cortisol and prolactin, particularly at higher doses. This is a disadvantage compared to ipamorelin, which is specifically selected for its minimal cortisol and prolactin impact. GHRP-6 tends to have a somewhat greater cortisol effect than GHRP-2.