Ipamorelinis a pentapeptide ghrelin-receptor agonist — the GH secretagogue that the community settled on as the default precisely because it does one thing cleanly: it triggers a pulsatile GH release without dragging prolactin, cortisol, or ACTH along for the ride. That selectivity is the whole story. Everything else about Ipamorelin follows from it.
What it is
Ipamorelin mimics ghrelin, the stomach’s hunger hormone, by binding the growth hormone secretagogue receptor (GHS-R1a) on pituitary somatotrophs. The result is a sharp GH pulse within 15–30 minutes of injection. Unlike GHRP-2 and GHRP-6 — the older ghrelin-receptor agonists — Ipamorelin does not meaningfully raise prolactin. That distinction matters: prolactin elevation at therapeutic doses is what causes libido suppression and contributes to the cortisol-driven anxiety and water retention associated with the older GHRPs. Ipamorelin’s appetite stimulation is also minimal at standard doses, which GHRP-6 users know is not guaranteed.
The pituitary is the rate limit for all secretagogues. Ipamorelin gives the pituitary a stimulus; what comes out depends on how well your pituitary responds. That output declines as you age. A well-timed 125 mcg injection produces roughly 0.5–0.7 IU of GH equivalent — confirmed by back-calculation from the published literature. It is modest and it is additive.
What the research actually shows
The mechanism is well-established: ghrelin receptor agonism drives pulsatile GH release, and Ipamorelin activates that receptor cleanly. There are studies examining Ipamorelin in the context of visceral fat reduction and non-alcoholic fatty liver disease. These are specific study designs — the comparators weren’t run in similar contexts, so head-to-head claims require caution.
The more honest framing is dosing-dependent and age-dependent. Younger users with a responsive pituitary can see 2–4 IU equivalent GH output from an optimized secretagogue stack. Older users face a pituitary that has already reduced its output, and secretagogue stimulus doesn’t change that ceiling. Ipamorelin itself doesn’t bypass the pituitary — it just asks it more politely than the older GHRPs did.
How people dose it
Standard reconstitution: 10 mg vial + 2 mL bacteriostatic water = 5 mg/mL (5,000 mcg/mL). Injection is subcutaneous, fasted.
- Low: 150 mcg per injection (3 units on a U-100 syringe), once daily
- Medium: 250–300 mcg per injection (5–6 units), once or twice daily
- High: 300 mcg per injection (6 units), two to three times daily
The saturation insight: at approximately 125–150 mcg per injection, the ghrelin receptor is at its ceiling for that pulse. Taking more in a single injection does not produce proportionally more GH — you’re not adding GH directly, you’re giving the pituitary a stimulus it can only respond to so much. Multiple well-timed lower-dose injections beat a single large one. The practical protocol: once before bed (the largest natural GH pulse occurs during deep sleep) or twice daily — morning pre-workout and before bed.
Fasted injection is non-negotiable. Food raises insulin, which raises somatostatin, which actively opposes the GH-releasing signal. Inject at least 2–3 hours after eating. Monitor fasted blood glucose weekly while running any GH secretagogue; if it climbs, Berberine (500–2,000 mg/day) is the preferred tool — it manages glucose without suppressing IGF-1 the way Metformin does.
What it stacks well with
The canonical pairing is CJC-1295. Ipamorelin hits the ghrelin receptor (GHS-R1a); CJC-1295 hits the GHRH receptor. Activating both arms of the GH axis simultaneously produces a substantially larger pulse than either alone — this dual-receptor logic is the reason the CJC-1295 + Ipamorelin blend became the most widely used injectable GH secretagogue protocol. If you want the combination without managing two vials, the pre-blended option is exactly that stack in one injection.
Tesamorelin + Ipamorelin is the preferred pairing for users who want maximum injectable GH secretagogue output and are dosing two to three times daily. Tesamorelin is the stronger GHRH-receptor agonist; Ipamorelin provides the ghrelin-receptor arm. DPP-4 inhibitors can extend the active window of injectable secretagogue peptides by inhibiting their enzymatic breakdown — relevant if you’re already on one of those medications for glucose management.
The honest caveats
- Pituitary ceiling is real.All secretagogues share this constraint. For users over 35–40 whose pituitary output has declined meaningfully, exogenous HGH becomes more cost-effective than secretagogue stacking.
- FDA Section 503a restricted. Ipamorelin is on the restricted compound list alongside CJC-1295, GHRP-2, GHRP-6, and MK-677. Not available by US compounding prescription.
- WADA prohibited. Ghrelin-receptor agonists are on the prohibited list. If you compete in a tested sport, this is disqualifying.
- Water retention and elevated fasting glucose are the dose-dependent side effects shared by all GH secretagogues. Monitor weekly.
- No standard workplace or military drug screens detect peptides. The risk is sport-specific.
The bottom line
Ipamorelin is the right ghrelin-receptor agonist for most users because it does the job without the prolactin and cortisol baggage of GHRP-2 and GHRP-6. The clean hormonal profile is not a marketing claim — it’s the pharmacological reason the community converged on it. Stack it with CJC-1295for dual-receptor coverage, time injections in a fasted state before bed or pre-workout, and understand the ceiling: you’re working with your pituitary, not around it.
For the reconstitution math, use the Ipamorelin calculator. For context on where Ipamorelin fits among all the GH secretagogues, read the GH secretagogues post. For the full protocol, refer to the free Peptide Guide.