Ipamorelin vs GHRP-2
The distinction that mattersBoth ghrelin receptor agonists. Ipamorelin is selective and spares cortisol and prolactin; GHRP-2 is more potent at releasing GH but raises both.
These are not equivalent in evidence GHRP-2 is rated 3/5 and Ipamorelin is rated 2/5 — a gap of 1 level on our scale. Similar marketing does not mean similar proof.
| Ipamorelin Research Use Only | GHRP-2 Limited Approval | |
|---|---|---|
| Evidence rating |
2/5 Limited
Evidence rating 2 out of 5: Limited
|
3/5 Moderate
Evidence rating 3 out of 5: Moderate
|
| Regulatory status | Investigational; phase 2 trials in postoperative ileus were discontinued. Not approved. Common in compounded wellness protocols. | Approved in Japan as a diagnostic agent for GH deficiency. Not approved in the US or EU for therapeutic use. |
| Category | Growth Hormone Axis | Growth Hormone Axis |
| Drug class | Selective ghrelin receptor (GHS-R1a) agonist — pentapeptide | Growth hormone-releasing peptide — synthetic hexapeptide ghrelin mimetic |
| Route | Subcutaneous (research) | Subcutaneous or intravenous |
| Half-life | ~2 hours | ~30–60 minutes |
| Studied in | Phase 2 trials for postoperative ileus (development stopped); animal studies on bone and GH secretion. | Diagnostic validation studies in Japan; short-term GH secretion studies; small studies in cachexia. |
| Who should avoid it |
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|
| Legal status | Not FDA-approved. FDA placed several GH-secretagogue peptides under increased compounding scrutiny. | Diagnostic approval in Japan only. Not lawful for therapeutic sale in the US. |
Benefits — Ipamorelin
- Selective GH release
Clean pharmacology: GH rises without the cortisol and prolactin spikes seen with hexarelin or GHRP-6.
- Minimal appetite stimulation
Unlike GHRP-6, it does not produce the intense hunger that makes those peptides impractical.
- Good short-term tolerability
Trial safety data in the ileus program were reassuring over short exposures.
- Synergy with GHRH analogs
The two mechanisms combine to produce a larger pulse than either alone.
Benefits — GHRP-2
- Strong, reliable GH release
Robust and reproducible enough to serve as an approved diagnostic stimulus for pituitary function.
- Appetite stimulation
Meaningful in cachexia and appetite-loss settings, where it has been studied in small trials.
- Oral and intranasal bioavailability studied
Alternative routes have been explored, unlike most peptides.
Risks & cons — Ipamorelin
- No proven clinical benefit
The trials that were run targeted gut motility and were discontinued. Body-composition and recovery claims are untested.
- Unapproved and unregulated
Available only through compounding or grey-market suppliers, with corresponding quality uncertainty.
- Glucose and insulin effects
Raising the GH axis can worsen insulin sensitivity over time.
- Receptor desensitisation
Continuous ghrelin-receptor stimulation blunts the response; effects diminish with sustained use.
- Head/injection-site reactions
Headache, flushing and local reactions are reported.
Risks & cons — GHRP-2
- Cortisol and prolactin elevation
Less selective than ipamorelin; repeated dosing can push these hormones outside normal ranges.
- No therapeutic approval
Approved only as a one-off diagnostic; chronic dosing has never been evaluated for safety.
- Tachyphylaxis
GH response declines with continued use.
- Insulin resistance
GH-axis class effect.
- Unregulated supply outside Japan
Sold as a research chemical with no quality assurance.
A comparison is not a recommendation. Neither column is being suggested for you. Which — if either — is appropriate depends on your diagnosis, history and medications, and that is a conversation for a qualified clinician.