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Ipamorelin vs GHRP-6
Growth HormoneIpamorelin and GHRP-6 both stimulate GH release through the ghrelin receptor but with vastly different selectivity. Ipamorelin is a third-generation peptide that selectively releases GH without increasing cortisol, prolactin, or appetite — even at doses 200x the effective dose. GHRP-6 is a first-generation peptide with broader hormonal effects including intense appetite stimulation, cortisol elevation, and prolactin increase.
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Side-by-Side Comparison
| Aspect | Ipamorelin | GHRP-6 |
|---|---|---|
| dosing | 200-300 mcg SubQ 2-3x daily | 100-300 mcg SubQ 2-3x daily on empty stomach |
| appetite | No appetite increase | Intense hunger within 20 minutes of injection |
| best for | Clean GH supplementation, fat loss, recovery, anyone wanting minimal side effects | Bulking phases where appetite increase is desired, maximum GH stimulation |
| mechanism | Highly selective GHS-R agonist — GH release only, no cortisol/prolactin/appetite effects | Broad GHS-R agonist — GH release plus strong ghrelin activation, cortisol and prolactin elevation |
| fda status | Not FDA-approved; research peptide | Not FDA-approved; research peptide |
| selectivity | Highly selective — does not raise cortisol or prolactin at any studied dose | Non-selective — raises cortisol, prolactin, and ghrelin alongside GH |
| side effects | Minimal — occasional transient head rush | Intense hunger, water retention, elevated cortisol/prolactin, lethargy |
Verdict
Ipamorelin is the clear winner for most use cases — same GH release with dramatically fewer side effects. GHRP-6 only makes sense when appetite stimulation is specifically desired (underweight, bulking). Ipamorelin has made GHRP-6 largely obsolete in modern protocols.