Ipamorelin vs GHRP-2: Which Is Right for You?
Both are synthetic ghrelin-receptor agonists that trigger growth-hormone release. Animal studies described ipamorelin as more selective, with little effect on cortisol or prolactin, while GHRP-2 (pralmorelin) raised both. Neither is FDA-approved; GHRP-2 is approved in Japan as a diagnostic agent.
Side-by-side comparison
| Ipamorelin | GHRP-2 | |
|---|---|---|
| Class | Ghrelin-receptor agonist (pentapeptide) | Ghrelin-receptor agonist (hexapeptide) |
| Selectivity (animal data) | GH release with little cortisol/ACTH or prolactin rise | GH release plus cortisol and prolactin rises |
| Approval | None | Japan (diagnostic, as pralmorelin) |
| FDA status | Not approved | Not approved |
| Sports anti-doping | Prohibited (WADA S2) | Prohibited (WADA S2) |
Complete comparison (2026)
Key takeaways
- Selectivity claims come mainly from a 1998 animal study of ipamorelin.
- Neither has an FDA-approved use.
- Both are prohibited in sport.
What are Ipamorelin and GHRP-2?
Ipamorelin is a synthetic five-amino-acid peptide that stimulates growth-hormone release through the ghrelin receptor; it was described in 1998 as the first selective growth hormone secretagogue and is not FDA-approved.
GHRP-2 (pralmorelin) is a synthetic growth hormone-releasing hexapeptide used diagnostically in Japan; it is not FDA-approved.
Mechanism differences
Both bind the growth hormone secretagogue receptor (GHS-R1a), the receptor for ghrelin, which stimulates pituitary GH release independently of GHRH.
Effectiveness
In a 1998 study in pigs and rats, ipamorelin released GH with potency similar to GHRP-6 but without raising ACTH or cortisol above levels seen with GHRH. GHRP-2 reliably raises GH in humans and is used in Japan for diagnostic GH stimulation testing.
Side effect profiles
GHRP-2 can raise cortisol, prolactin and appetite. Human safety data for ipamorelin come from small developer trials. "Research" products have no regulatory oversight of purity or dose.
Dosing & administration
No US label exists for either. We don't publish doses.
Cost
Both are sold as "research use only" products; see the compound pages for vendor listings.
FDA & regulatory status
Neither is FDA-approved; products labeled research-use-only are not for human use.
Who should choose which
There is no evidence-based reason to choose either for personal use.
What the evidence does not show
- Head-to-head human trials.
- Long-term safety.
Frequently asked questions
Is ipamorelin better than GHRP-2?
Animal studies suggest ipamorelin is more selective for GH release; there are no head-to-head human trials.
Is GHRP-2 approved anywhere?
Yes. As pralmorelin it is approved in Japan as a diagnostic agent for growth-hormone deficiency.
Do they show up in drug tests?
Both are on WADA's prohibited list under growth-hormone secretagogues.
References
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