The older-generation GHRPs — GHRP-2 is the pharma-developed version (pralmorelin), GHRP-6 is the hunger-inducing outlier. Both have largely been replaced by ipamorelin in modern protocols.
GHRP-2 (pralmorelin) and GHRP-6 are synthetic hexapeptides developed in the 1980s–1990s as growth hormone secretagogues. Both activate the ghrelin receptor to trigger GH release from the pituitary, but with different secondary profiles:
GHRP-2 was advanced to clinical trials (under the name pralmorelin) in Japan but never fully commercialized. Both are now primarily research chemicals.
Not FDA approved. WADA prohibited (S2). Pralmorelin is still used as a diagnostic agent for GH deficiency in Japan.
Both bind GHS-R1a to trigger GH release. Potency: hexarelin > GHRP-6 ≥ GHRP-2 > ipamorelin. All produce a GH pulse; selectivity and side-effect profile differ.
GHRP-6 is a stronger functional ghrelin mimetic in the hypothalamic hunger circuit than its peers. Historically used for underweight cachectic patients — now avoided by most users who don’t want the appetite boost.
Both raise these modestly — less than hexarelin, more than ipamorelin. The main reason both have lost ground to ipamorelin over the last decade.
| Benefit | Evidence |
|---|---|
| GH elevation | Both produce reliable GH pulses; GHRP-2 slightly larger than GHRP-6 in head-to-head studies |
| Appetite stimulation | GHRP-6 meaningful; GHRP-2 modest. Useful for hard-gainers / underweight patients |
| Body composition | Modest lean mass gains + fat loss over 8–12 weeks |
| Sleep | Pre-bed dose supports slow-wave sleep |
| Diagnostic use (GHRP-2) | Pralmorelin approved in Japan as a GH-deficiency diagnostic agent |
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Start Tracking Free100 mcg is the commonly cited saturation dose in practitioner protocols — more is reported to produce more side effects rather than a bigger GH pulse. Note that PMID 9285939 tested GHRP-2 at 1–2 mcg/kg IV in adults (~70–140 mcg range) and showed dose-dependent GH responses across that range, so the saturation point is approximate and may vary with body weight. Scale number of pulses per day (up to 3), not per-dose, if you want more total GH exposure.
GHRP + GHRH synergy applies here too. GHRP-2 + CJC-1295 or + sermorelin produces a larger pulse than either alone. Most users who want this stack use ipamorelin instead for the cleaner profile.
5 mg vial + 2.5 mL BAC water = 2000 mcg/mL
| Dose | Volume | Syringe Units |
|---|---|---|
| 100 mcg | 0.05 mL | 5 units |
| 150 mcg | 0.075 mL | 7.5 units |
Pre-filled with a typical GHRP-2 and GHRP-6 setup. Edit any field — the draw updates live.
Insulin syringe — 100 units = 1 mL
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GHRP-2 and GHRP-6 is a research peptide not approved by the FDA for human use. It is sold only as a research chemical, and StackTrax does not endorse or facilitate personal use.
Quality varies enormously among research-chemical suppliers. At minimum, look for:
StackTrax’s preferred partner NextGen Peptides does not currently carry GHRP-2 and GHRP-6in their catalog, which is why you don’t see a direct purchase link here. Other major research-chemical suppliers carry it; we don’t specifically recommend one for this compound.
Build your protocol, log every dose, monitor your body's response, and get reminders so you never miss a dose.
Start Tracking FreeGHRPs are synthetic hexapeptides developed in the 1980s and 1990s as growth hormone secretagogues. They bind the ghrelin receptor (GHS-R1a) on pituitary somatotrophs to trigger a GH pulse — a different pathway from the GHRH receptor that sermorelin/CJC-1295/tesamorelin target. The named GHRP family includes GHRP-2 (pralmorelin), GHRP-6, hexarelin, and ipamorelin. None of them are FDA-approved for hypertrophy or longevity use; all are WADA-prohibited.
All four are ghrelin-receptor agonists that produce a GH pulse, but their secondary profiles differ. Potency ranking is roughly hexarelin > GHRP-6 >= GHRP-2 > ipamorelin. GHRP-2 has moderate potency with measurable cortisol/prolactin/ACTH stimulation. GHRP-6 has similar GH effect but a dramatically stronger hunger response — historically used as an appetite stimulant. Hexarelin is the most potent but causes the most cortisol/prolactin elevation. Ipamorelin is the cleanest (minimal cortisol/prolactin/hunger), which is why it has largely replaced GHRP-2 and GHRP-6 in modern protocols.
GHRP-6 is a stronger functional ghrelin mimetic in the hypothalamic hunger circuit than its peers. Ghrelin is the bodys hunger hormone, and GHRP-6 mimics that signaling more strongly than GHRP-2 or ipamorelin do. This was historically useful in underweight cachectic patients, but most modern users avoid GHRP-6 specifically because they do not want the appetite boost. GHRP-2 produces modest hunger; ipamorelin essentially none.
Not FDA approved for any indication in the US. WADA prohibited under category S2 (Peptide Hormones, Growth Factors and Related Substances). GHRP-2 (pralmorelin) is approved in Japan as a diagnostic agent for GH deficiency, but is not commercialized as a therapeutic. In the US all GHRPs are sold as research chemicals only.
Community-practice dosing for both GHRP-2 and GHRP-6 is 100–150 mcg subcutaneously, 1–3 times daily, on an empty stomach (more than 2 hours post-meal). 100 mcg is commonly cited as the saturation dose — more reportedly produces more side effects rather than a bigger GH pulse. PMID 9285939 tested GHRP-2 at 1–2 mcg/kg IV in adults (roughly 70–140 mcg) and showed dose-dependent GH responses across that range. To scale total GH exposure, increase the number of pulses per day (up to 3) rather than the per-dose amount.
GHRPs hit the ghrelin receptor; GHRH analogs like CJC-1295 or sermorelin hit the GHRH receptor. Stacking the two stimulates GH release through both pathways simultaneously, producing a larger pulse than either alone. GHRP-2 plus CJC-1295 works, but most users who want the GHRH-plus-GHRP combo now use ipamorelin in place of GHRP-2 because of the cleaner cortisol/prolactin/hunger profile.
Yes, both raise cortisol and prolactin modestly — less than hexarelin, more than ipamorelin. PMID 9285939 describes GHRP-2 as a "super-analog of GHRP-6" with stronger overall GH effect and measurable prolactin, ACTH, and cortisol stimulation. This off-target endocrine activation is the main reason both compounds have lost ground to ipamorelin over the last decade.
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