Ipamorelin
Also known as NNC 26-0161, Ipamorelin acetate
Ipamorelin is a pentapeptide that triggers growth hormone release through the ghrelin receptor without the cortisol, prolactin, or hunger spikes seen with older GHRPs. It is the most popular GHRP in the community, usually stacked with a GHRH analog.
Overview
Ipamorelin is a five amino acid synthetic peptide developed by Novo Nordisk in the 1990s as a growth hormone secretagogue. It belongs to the GHRP family alongside GHRP-2, GHRP-6, and hexarelin, all of which act on the ghrelin receptor (GHS-R1a). What set ipamorelin apart in the original animal work was selectivity. At doses that released as much growth hormone as GHRP-6, it produced no meaningful rise in ACTH, cortisol, or prolactin, and in humans it does not cause the sharp hunger that GHRP-6 is known for.
Human trials were limited. Novo Nordisk ran Phase 1 and Phase 2 studies, including one in patients after abdominal surgery looking at whether ipamorelin could speed recovery of bowel function. The compound was well tolerated and produced dose dependent growth hormone release, but the ileus trial did not show a convincing benefit and development was dropped. There are no published long term studies on body composition, sleep, or aging in healthy adults, so most of what people report about it comes from community experience rather than controlled data.
The reason it dominates community protocols is the combination of a clean side effect profile and genuine synergy with GHRH analogs. On its own, ipamorelin produces a moderate growth hormone pulse. Paired with Mod GRF 1-29 or tesamorelin, the two pathways reinforce each other and release considerably more than either alone. That pairing, injected before bed on an empty stomach, is probably the single most common growth hormone protocol outside of prescription growth hormone.
How it works
Ipamorelin is an agonist at the growth hormone secretagogue receptor, the same receptor activated by the stomach hormone ghrelin. Activation in the pituitary raises intracellular calcium in somatotrophs and triggers growth hormone release, while activation in the hypothalamus increases GHRH output and reduces somatostatin, which amplifies the pulse. Unlike GHRP-6 and hexarelin, ipamorelin shows little activity at the pathways that drive ACTH and prolactin release, so cortisol stays flat. It also appears to have a weaker effect on the appetite circuits, which is why hunger is rarely reported. The growth hormone released then acts on the liver to raise IGF-1.
What the research shows
- rodentIpamorelin released growth hormone as potently as GHRP-6 in rats and pigs without raising ACTH or cortisol.
- human pilotSingle subcutaneous doses in healthy men produced dose dependent growth hormone release with no significant change in prolactin or cortisol.
- human RCTA Phase 2 trial of ipamorelin for postoperative ileus after bowel resection showed acceptable safety but did not reach its efficacy endpoint.
- rodentIpamorelin increased bone mineral content in growing rats over 12 weeks, mediated partly by growth hormone.
Evidence labels: rodent and in vitro mean no human data for that finding. Human pilot means small, often uncontrolled. Human RCT means randomized and controlled. Clinical means an approved drug with regulatory data.
Dose calculator
U-100 insulin syringeUnits are a volume on the syringe, not an amount of peptide. Concentration changes every time you change the water volume. The standalone calculator explains the math.
Dosing and protocol
100 mcg is near saturation for GH release; 200-300 mcg is common when used alone
8-16 weeks, then a few weeks off
Empty stomach, most often right before bed. Additional doses on waking or after training are common in three-a-day protocols.
| Vial | Suggested water | Concentration | Low dose draw |
|---|---|---|---|
| 5 mg | 2 mL | 2.5 mg/mL | 4 units |
| 10 mg | 3 mL | 3.333 mg/mL | 3 units |
Lyophilized: freezer or fridge, away from light. Reconstituted: fridge 2-8C, use within 4 weeks.
Cautions
- ▲Headache, flushing, and lightheadedness right after a dose are common early on and usually fade.
- ▲Water retention and tingling in the fingers can show up at higher doses or when stacked heavily.
- ▲Eating within 30 minutes on either side of a dose blunts the growth hormone response.
- ▲Avoid raising growth hormone and IGF-1 with any active or prior hormone sensitive cancer.
- ▲It is not as potent as GHRP-2 or hexarelin on its own; the selectivity comes with a smaller pulse.
Commonly stacked with
The standard pairing; GHRH plus GHRP gives a synergistic pulse several times larger than either alone.
Same synergy with a GHRH analog that has stronger human evidence for visceral fat reduction.
Adds sharp pulses on top of the continuous stimulation from the DAC version.
Frequently asked
Why is ipamorelin considered the cleanest GHRP?
Because it releases growth hormone without the side effects that come with the older ones. GHRP-6 makes you ravenous, hexarelin raises cortisol and prolactin, and GHRP-2 does a bit of both. Ipamorelin leaves those hormones mostly alone at normal doses.
Do I need to stack it with CJC-1295?
You do not have to, but almost everyone does. The GHRH analog and the GHRP work through different receptors and the combined growth hormone pulse is much larger than either alone. Running ipamorelin solo gives a modest effect that many people find underwhelming.
Will it make me hungry?
Usually not, or only mildly. It acts on the ghrelin receptor so some people notice a small appetite bump, but it is nothing like GHRP-6. If hunger is a problem, ipamorelin is the GHRP to use.
How long does it take to see results?
Deeper sleep often shows up within a week or two. Body composition changes, better recovery, and skin improvements take 2-3 months of consistent use, and the effects are gradual rather than dramatic.
References
- Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology, 1998
- Phase 2 study of ipamorelin for the management of postoperative ileus after bowel resection. Neurogastroenterology and Motility, 2014
- Effects of ipamorelin on bone growth and bone mineral content in rats. Growth Hormone and IGF Research, 2001