At a glance: Ipamorelin is a five-amino-acid synthetic peptide that triggers growth hormone release by mimicking the hormone ghrelin. It is known for being selective, raising growth hormone without much effect on cortisol or prolactin. Its only major clinical trial, for recovery after bowel surgery, failed to beat placebo. It is not FDA-approved, an FDA advisory panel voted 0 to 12 against allowing it in compounding, and it is banned in sport.
What is ipamorelin?
Ipamorelin is a synthetic pentapeptide (five amino acids) developed by Novo Nordisk in the 1990s and first described in 1998 as the first selective growth hormone secretagogue, a compound that makes the pituitary gland release growth hormone. It was derived from an older peptide called GHRP-1.
It belongs to the same family as GHRP-2 and GHRP-6, but those older peptides also raise the stress hormone cortisol and the hormone prolactin. Ipamorelin's selling point is that, in studies, it largely did not.
How does ipamorelin work?
- Activates the ghrelin receptor (growth hormone secretagogue receptor) on the pituitary, the same receptor used by ghrelin, the "hunger hormone"
- Triggers a pulse of growth hormone, which then raises IGF-1 from the liver
- Selective: in animal and human studies it did not meaningfully raise cortisol, ACTH or prolactin, or affect other pituitary hormones
- Short-acting: its half-life in people is about 2 hours, producing a brief growth hormone pulse
- Different pathway from CJC-1295 and sermorelin, which act on the GHRH receptor; this is why they are often combined
What the research shows so far
| Study | Who was studied | Main finding |
|---|---|---|
| Raun et al., 1998 | Animals | Strong, selective growth hormone release without raising cortisol or prolactin |
| Gobburu et al., 1999 | Healthy human volunteers | Measured how ipamorelin is absorbed and cleared and how it triggers growth hormone; half-life about 2 hours |
| Beck et al., 2014 (Helsinn, phase 2) | Patients after bowel surgery (postoperative ileus) | No significant difference from placebo on recovery; development was discontinued for lack of efficacy |
| Muscle, fat loss, sleep or anti-aging | No clinical trials | Claims come from user reports and general growth hormone effects |
Why it gets attention
- "Cleaner" growth hormone boost: marketed as selective, without the cortisol and hunger effects of older peptides
- Body composition, recovery and sleep claims in fitness and wellness communities
- The CJC-1295 + ipamorelin stack, one of the most popular peptide combinations sold online
- Use in pro sports: athletes in MLB and the NBA have been suspended after testing positive
How it is given
Ipamorelin is injected under the skin, often in the evening or combined with CJC-1295 in the same injection. There is no FDA-approved product and no established human dose for any use, and this page does not provide dosing guidance.
What about side effects?
Reported side effects are generally mild: injection-site reactions, headache, flushing, lightheadedness and water retention. Because it raises growth hormone and IGF-1:
- Blood sugar can rise, a concern for people with diabetes or prediabetes
- High IGF-1 over time is a theoretical cancer concern for people with cancer or a history of it
- Long-term safety is unknown: no study has followed people using it for months or years
- Product quality: online "research" products may be mislabeled, contaminated or non-sterile
Regulatory status
- Not FDA-approved for any use.
- In September 2024 ipamorelin was removed from FDA's Category 2 safety-concern list after its compounding nomination was withdrawn.
- At the October 29, 2024 meeting, FDA recommended against adding it to the compounding list, and its advisory committee reportedly voted 0 to 12, with 1 abstention, citing a lack of safety and effectiveness data for growth hormone deficiency and postoperative ileus.
- It was not part of the 2026 peptide reviews, so it cannot be legally compounded.
- It is prohibited by the World Anti-Doping Agency as a growth hormone secretagogue, and is banned in major US pro sports.
How it compares to other growth hormone peptides
| Ipamorelin | CJC-1295 | Tesamorelin | |
|---|---|---|---|
| Type | Ghrelin mimetic (5 amino acids) | GHRH analog | GHRH analog |
| Duration | About 2 hours | Hours (no DAC) to about a week (DAC) | Daily injection |
| Human evidence | Small studies; failed phase 2 trial | Small studies; trial halted in 2006 | Large randomized trials |
| US status | Not approved; not compoundable | Not approved; not compoundable | FDA-approved for HIV-associated belly fat |
The bottom line
Ipamorelin is a well-designed, selective growth hormone releaser with clean results in early studies. But its one real clinical test failed, it was never developed into a medicine, and an FDA advisory panel unanimously rejected it for compounding. Claims about muscle, fat loss and sleep are not backed by trials. Anyone concerned about growth hormone, body composition or aging should see a clinician; true growth hormone deficiency has approved, monitored treatments.
Frequently asked questions
What is Ipamorelin?
A five-amino-acid peptide that acts on the ghrelin receptor to trigger growth hormone release, with less effect on other hormones than older compounds.
How is Ipamorelin taken?
Injection (trials).
Is Ipamorelin FDA approved?
Not approved.
That means no regulator has reviewed its safety, effectiveness or manufacturing quality for this use.
What has research shown about Ipamorelin?
- Growth hormone release in animal and early human studies.
- Recovery of bowel function after surgery in a phase 2 trial.
What side effects have been reported?
- Headache
- Injection site reactions
Serious or less common risks are listed in the Side Effects section above.
What is still unknown about its safety?
Most of it. Ipamorelin has not been through the trials that establish long-term safety in people, and products sold online are made by unregulated labs. Independent testing of online peptides has repeatedly found contents that do not match the label.
References
- Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology. 1998;139(5):552-561. View source
- Gobburu JV, et al. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharmaceutical Research. 1999;16(9):1412-1416. View source
- Beck DE, et al. Prospective, randomized, controlled, proof-of-concept study of the ghrelin mimetic ipamorelin for the management of postoperative ileus. International Journal of Colorectal Disease. 2014;29(12):1527-1534. View source
- Reed Smith: FDA moves certain peptide bulk drug substances from Category 2; PCAC review (October 2024). View source
- Project Biohacking: CJC-1295 and ipamorelin PCAC votes and 503A status. View source
- Rite Aid: Ipamorelin overview. View source