The first effect of ipamorelin comes within tens of minutes. In healthy men the growth hormone peak came 40 minutes after the start of the infusion, and ipamorelin itself left the blood with a half-life of 2 hours. Effects in tissues were measured over weeks: after 15 days rat bones grew in length faster, and after 12 weeks they held more minerals. If you want to know what to expect from ipamorelin and when, below is a timeline from the studies that can be read today.
How does ipamorelin work?
Ipamorelin mimics ghrelin and prompts the pituitary to release growth hormone. It is a pentapeptide, a chain of five amino acids, developed in the late 1990s. It acts through the GHS-R1a receptor, the same one used by ghrelin, known as the hunger hormone.
Each dose gives one clear pulse of growth hormone, after which the level returns to baseline. The body releases growth hormone in waves on its own, so this rhythm is close to the natural one. In a 1998 study in pigs ipamorelin did not raise cortisol or ACTH more than GHRH, even at doses over 200 times higher than the effective one. Why ipamorelin is called a clean GHRP is explained in a separate guide on ipamorelin and its selectivity.
How soon does ipamorelin raise growth hormone?
The most precise measurement comes from a 1999 study in Pharmaceutical Research. It tested five doses, each in eight healthy men. Ipamorelin was given as a 15-minute intravenous infusion and growth hormone in the blood was measured at short intervals.
- Growth hormone peak: after 0.67 hours, that is about 40 minutes from the start of the infusion.
- Shape of the response: one pulse, then a fall to a level close to zero at every dose.
- Half-life of ipamorelin: 2 hours.
- Dose dependence: the blood concentration rose in proportion to the dose given.
Growth hormone responded to each of the five doses, including the lowest. Differences between people were larger in the growth hormone response than in the ipamorelin concentration itself.
What effects did ipamorelin show in studies?
The longer studies were run in animals, because no one has yet measured body composition after ipamorelin in humans. The results form a clear timeline, from days to months.
| Time of use | Study | What changed |
|---|---|---|
| 2 weeks | mice, Biochemical and Biophysical Research Communications 2001 | body weight 15 percent higher, more food eaten |
| 15 days | rats, Growth Hormone and IGF Research 1999 | bone length growth up from 42 to 52 µm a day, greater weight gain |
| 12 weeks | rats, Journal of Endocrinology 2000 | more minerals in the tibia and vertebrae, larger bone dimensions |
| 3 months | rats on steroids, Growth Hormone and IGF Research 2001 | calf muscle strength preserved, bone formation four times faster |
In the 1999 study growth depended on the dose: at three rising doses bones grew by 44, 50 and 52 µm a day. In the 2000 study the extra minerals came from larger bones, not from greater bone density.
What does ipamorelin do to muscle and body weight?
The most interesting result for people who train comes from a 2001 study. For three months rats were given high doses of the steroid methylprednisolone, which breaks down muscle and blocks bone rebuilding. Some of them received ipamorelin at the same time.
In the ipamorelin group the maximum strength of the calf muscles was significantly greater than in the steroid-only group. Formation of new bone on its surface was as much as four times faster. The authors write that ipamorelin counteracted the loss of muscle strength and bone formation caused by the steroid.
A 2024 study in Physiology and Behavior pointed the same way. Ferrets received cisplatin, a cancer drug that strongly suppresses appetite and body weight. Ipamorelin reduced the loss of body weight on day three by about 24 percent.
In animal studies ipamorelin raised body weight at every observation point. In mice the gain was 15 percent in two weeks and did not grow further up to week nine. The mice ate more and had a larger share of fat tissue, and the authors link this to greater food intake that does not depend on growth hormone.
For you this is a practical hint.
When building mass a bigger appetite helps, and when cutting it is worth keeping an eye on food. How ipamorelin compares with GHRP-2 and GHRP-6 is shown in the guide on the differences between GHRP-2, GHRP-6 and ipamorelin.
What is known from studies in humans?
In humans ipamorelin is described mainly in two papers. The first is the 1999 study of growth hormone release in healthy men described above. The second, from 2014, tested the return of bowel function after surgery in 114 patients.
In that second study patients on ipamorelin tolerated a solid meal after a median of 25.3 hours, and those on placebo after 32.6 hours. The difference was not statistically significant. We found no studies of body composition, strength or recovery in humans, so the effects on physique are known today from animal studies.
What is ipamorelin combined with?
Ipamorelin is most often combined with a GHRH analogue such as CJC-1295. Both peptides trigger growth hormone release, but by different routes: ipamorelin through the ghrelin receptor and CJC-1295 through the GHRH receptor. Why this pair is so popular is explained in the guide CJC-1295 and ipamorelin, why together.
Tesamorelin is also a GHRH analogue, and the only peptide in this group approved as a medicine. Its effect on belly fat is described in the guide tesamorelin and belly fat. The effect of growth hormone pulses on sleep is covered in the guide on growth hormone peptides and sleep.
Where to buy ipamorelin?
The shop has ipamorelin in stock from three brands, always 10 mg. The Bio-Peptide version comes at the lowest price together with Genheal and includes two ampoules of solvent, and the Nouveaux Ltd. version comes as a ready dual-chamber cartridge.
| Product | Pack | Price |
|---|---|---|
| Ipamorelin 10 mg Bio-Peptide | vial and two 1 ml ampoules of solvent | 40 EUR |
| Ipamorelin 10 mg Genheal | vial and one 1 ml ampoule of solvent | 40 EUR |
| Ipamorelin 10 mg Nouveaux Ltd. | dual-chamber cartridge with 1 ml of solvent | 50 EUR |
| Ipamorelin and CJC-1295 Combo 10 mg Nouveaux | dual-chamber cartridge, both peptides together | 40 EUR |
Everything about the molecule is collected on the ipamorelin page. The products are material for laboratory research, not a medicine, and there is no dosing protocol backed by studies in humans. Athletes are bound by the WADA ban all year round.
Frequently asked questions
How soon does ipamorelin work?
In healthy men the growth hormone peak came about 40 minutes after the start of the infusion. The hormone level then fell back to baseline, and ipamorelin had a half-life of 2 hours.
What effects does ipamorelin have?
In animal studies it sped up bone growth and increased bone mineral content and body weight. In rats on steroids it protected muscle strength.
After how many weeks did studies show effects of ipamorelin?
Faster bone growth in rats was measured after 15 days, weight gain in mice after two weeks, and more bone minerals after 12 weeks.
Does ipamorelin increase appetite?
In mice it increased food intake, and body weight rose by 15 percent in two weeks. We found no studies of appetite after ipamorelin in humans.
Has ipamorelin been studied in humans?
Yes. The most important are the 1999 study of growth hormone release in healthy men and the 2014 study of bowel function after surgery in 114 patients.
How much does ipamorelin cost in the shop?
Ipamorelin 10 mg costs 40 EUR from Bio-Peptide and Genheal and 50 EUR from Nouveaux Ltd. All are in stock.
Sources
- Gobburu JV, Agersø H, Jusko WJ, Ynddal L. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharmaceutical Research, 1999, 16(9): 1412-1416. https://doi.org/10.1023/a:1018955126402
- Raun K, Hansen BS, Johansen NL et al. Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology, 1998, 139(5): 552-561. https://doi.org/10.1530/eje.0.1390552
- Johansen PB, Nowak J, Skjaerbaek C et al. Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. Growth Hormone and IGF Research, 1999, 9(2): 106-113. https://doi.org/10.1054/ghir.1999.9998
- Svensson J, Lall S, Dickson SL et al. The GH secretagogues ipamorelin and GH-releasing peptide-6 increase bone mineral content in adult female rats. Journal of Endocrinology, 2000, 165(3): 569-577. https://doi.org/10.1677/joe.0.1650569
- Andersen NB, Malmlöf K, Johansen PB et al. The growth hormone secretagogue ipamorelin counteracts glucocorticoid-induced decrease in bone formation of adult rats. Growth Hormone and IGF Research, 2001, 11(5): 266-272. https://doi.org/10.1054/ghir.2001.0239
- Lall S, Tung LY, Ohlsson C et al. Growth hormone (GH)-independent stimulation of adiposity by GH secretagogues. Biochemical and Biophysical Research Communications, 2001, 280(1): 132-138. https://doi.org/10.1006/bbrc.2000.4065
- Lu Z, Ngan MP, Liu JYH et al. The growth hormone secretagogue receptor 1a agonists, anamorelin and ipamorelin, inhibit cisplatin-induced weight loss in ferrets. Physiology and Behavior, 2024, 284: 114644. https://doi.org/10.1016/j.physbeh.2024.114644
- Beck DE, Sweeney WB, McCarter MD. Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. International Journal of Colorectal Disease, 2014, 29(12): 1527-1534. https://doi.org/10.1007/s00384-014-2030-8
- Stanley TL, Grinspoon SK. Effects of growth hormone-releasing hormone on visceral fat, metabolic, and cardiovascular indices in human studies. Growth Hormone and IGF Research, 2015, 25(2): 59-65. https://doi.org/10.1016/j.ghir.2014.12.005