Apex Laboratory · Compound explained · Evidence checked September 8, 2026
Ipamorelin is a synthetic five-residue peptide that stimulates growth hormone release through the ghrelin receptor. Human studies confirm a GH response, but that is not proof of muscle growth, belly-fat loss, better sleep or long-term safety.
The key distinction: releasing a hormone and improving an outcome are different findings. The published randomized bowel-surgery trial did not show a significant clinical benefit. A second, larger trial is registered as completed, but its registry has no posted results.
What is Ipamorelin and what does it do?
Ipamorelin is a growth hormone secretagogue: a compound that prompts release of the body’s own GH. It is not growth hormone itself, testosterone or a form of CJC-1295. Its development name is NNC 26-0161. The original pharmacology paper described GH release in rat pituitary cells, rats and swine. Raun and colleagues, 1998.
- Reference form
- Free base
- Formula
- C₃₈H₄₉N₉O₅
- Molar mass
- 711.9 g/mol
The sequence contains nonstandard amino-acid building blocks and an amidated end. The PubChem reference structure describes the parent molecule. An acetate salt, a formulated product and the mass printed on a vial need their own specifications; the reference molecular weight alone does not verify them.
How does Ipamorelin work?
It activates the growth hormone secretagogue receptor, usually written GHS-R1a. Ghrelin is the body’s naturally occurring ligand for this receptor. The receptor was characterized in 1996, before ghrelin itself was identified in 1999. Receptor discovery · Ghrelin discovery.
This signaling route differs from the growth hormone-releasing hormone receptor used by GHRH analogues. Both can affect GH release, but a shared downstream hormone does not make the compounds interchangeable. Nor does it establish an effective combination for a particular person.
What does “selective” actually mean?
Hormone measurements in swine
Ipamorelin stimulated GH without an ACTH or cortisol response significantly different from the GHRH comparator. GHRP-2 and GHRP-6 raised those hormones under the tested conditions.
A side-effect-free human treatment
The experiment did not measure long-term human safety, muscle gain, sleep improvement or a reliable testosterone effect. A selective measured response is narrower than a universal safety claim.
The same paper found no change in FSH, LH, prolactin or TSH with the tested secretagogues in swine. The species, comparator and measurements matter. Read the original selectivity report.
What have the human trials shown?
The human evidence includes a short pharmacokinetic study, a published surgical trial and a separate larger registry entry. They answer different questions. Treating all of them as “proof that Ipamorelin works” loses the endpoint that was actually tested.
A hormone response, not a fitness trial
Healthy male volunteers received intravenous Ipamorelin across five dose levels, with eight subjects at each level. Researchers measured the peptide and GH, then modeled their relationship. They did not test muscle growth, fat loss or sleep quality. Gobburu and colleagues.
Recovery after bowel surgery
The randomized placebo-controlled study included 114 people in its safety and modified intention-to-treat analyses. Its main question was whether patients could tolerate a solid meal sooner after surgery. Beck and colleagues, 2014 · Trial record.
Completed does not mean a positive result
NCT01280344 is a separate randomized phase 2 gastrointestinal-recovery study, completed in May 2014. Its record was last updated in April 2017 and has no posted results as checked September 8, 2026. The reviewed source set did not identify a results paper for it; this is not another 320 people with demonstrated benefit.
The published trial’s main efficacy result
Median time from first treatment to the first tolerated standardized solid meal:
p = 0.15. The difference was not statistically significant.
The authors reported no significant differences in the key or secondary efficacy analyses. These values describe hospitalized bowel-resection patients, not exercise recovery. Published primary report.
Does the newer 2026 registry entry change the answer?
NCT07717866, first posted July 21, 2026, lists 52 actual participants in an observational study of a multicomponent program. Ipamorelin appears among several possible components of “physiological supplementation,” alongside other interventions. The record is active, not recruiting, with no posted results. It does not isolate Ipamorelin’s effects, and 52 enrolled participants should not be described as 52 people proven to have received Ipamorelin.
What is the half-life of Ipamorelin?
The 1999 intravenous volunteer study reported a terminal plasma half-life of about two hours. It also described a single episode of GH release, peaking around 0.67 hours. These are different measurements from the same study. Human PK/PD report.
Terminal half-life
How rapidly the measured peptide concentration declined in the terminal phase of that intravenous study.
GH peak
When the study’s GH response reached its peak. It is not the peptide’s half-life or a duration of clinical benefit.
Neither value establishes a personal dosing interval, an everyday schedule or the behavior of an oral or subcutaneous formulation. A rat study’s approximately 20% nasal bioavailability is also not a human estimate. Rat route-comparison study.
A separate analytical study examined human urine after nasal administration, with one volunteer per tested compound. Its Ipamorelin findings help identify parent material and metabolites; they do not establish clinical effectiveness or a reliable absorption percentage. A urine detection window is not a plasma half-life. Human metabolite-detection study.
A separate receptor-assay study detected GHS-R1a binding activity in excreted urine after nasal administration of several peptides, including Ipamorelin. Such activity can reflect intact compounds plus active metabolites; it is not a duration-of-benefit measurement. Primary receptor-assay study.
Does Ipamorelin build muscle or reduce belly fat?
The human studies reviewed here do not establish those outcomes. A GH increase cannot substitute for an actual measurement of lean mass, strength or abdominal fat.
Ipamorelin increased adiposity in mice
In a 2001 study, Ipamorelin increased relative fat-pad weights in both GH-deficient and GH-intact mouse groups. Additional measurements found increased relative body fat, with feeding-related changes in GH-intact mice. The authors concluded that GH secretagogues can increase fat through mechanisms that do not depend on GH.
This does not predict a person’s weight change. It does disprove the simple argument that “more GH automatically means less fat.” Lall and colleagues.
In glucocorticoid-treated rats, Ipamorelin counteracted reductions in muscle strength and bone formation. Other rat work reported less postoperative weight loss under steroid treatment and reduced nitrogen wasting. These are models of catabolic stress, not demonstrations of muscle gain in healthy athletes. Muscle and bone experiment · Steroid-treated rat study · Nitrogen-balance study.
Does it raise testosterone?
No reliable human testosterone increase is established by the reviewed studies. A 2024 Ipamorelin acetate experiment reported reproductive-axis changes in the fish Oreochromis mossambicus, including higher LH and 11-ketotestosterone. Those are fish findings, not a human testosterone-replacement result. Primary fish study.
What other benefits have researchers investigated?
Bone growth rather than universally denser bone
A rat study found increased longitudinal bone growth without a rise in total circulating IGF-I. A separate 12-week experiment found larger bones and more mineral content, but unchanged volumetric bone density and unchanged mineral content relative to bodyweight. “More bone mineral” was not equivalent to denser bone tissue. Longitudinal-growth study · Bone-size and density study.
Gut movement and experimental pain responses
Rat postoperative models showed faster bowel transit or gastric emptying, with results depending on the outcome and exposure conditions. A separate rat hypersensitivity study found reduced pain-related responses that a ghrelin-receptor antagonist blocked. These findings support further mechanistic research; the positive animal results did not become a significant benefit in the published human bowel-surgery trial. Colonic transit · Gastric emptying · Hypersensitivity experiment.
Weight loss during chemotherapy in ferrets
A 2024 experiment found that Ipamorelin and anamorelin reduced part of the weight loss associated with cisplatin in ferrets. Neither prevented vomiting under the tested peripheral-administration conditions. The additional central anti-emetic result belonged to anamorelin, not Ipamorelin. Primary ferret comparison.
Chronic exposure also changed aspects of GH storage and response in pituitary cultures derived from treated young female rats. This helps investigate hormone regulation; it does not establish that daily human use remains effective indefinitely. Somatotroph-cell study.
What are Ipamorelin’s side effects and FDA status?
“Selective” should not be read as “no side effects.” The studied populations, route, duration and product quality all limit what can be concluded about safety.
Read the safety findings alongside the trial’s reassuring abstract
FDA’s 2024 review describes nausea, vomiting and abdominal distention in the surgical trial, plus higher rates of low potassium, insomnia and high glucose at discharge in the Ipamorelin group. It also records two fatal serious adverse events in treated patients who developed major postoperative complications.
FDA explicitly says it is unclear whether the deaths were related to Ipamorelin. Reporting those events is necessary; attributing them definitively to the peptide would overstate the evidence. FDA primary review, printed pages 33–35.
The published trial’s “well tolerated” conclusion does not establish long-term safety or safety by another route. FDA also discusses uncertainty about GH/IGF-related risks and immune reactions associated with peptide aggregates or impurities. That uncertainty is not resolved by a purity percentage.
Was Ipamorelin “banned”?
The precise FDA status is more useful than the broad word “banned.” No Ipamorelin approval was identified in the current Drugs@FDA query; FDA’s evaluation states it is not a component of an FDA-approved drug. Its current compounding safety page makes two distinct entries:
Ipamorelin acetate remains listed under the 503B interim policy because of potential significant safety risks.
The same substance also appears in the withdrawn-nominations table. Withdrawal of a nomination is not approval or a finding of safety.
Status checked September 8, 2026. FDA identifies aggregation, peptide-impurity and characterization concerns, and insufficient information for certain other injectable routes. This describes the cited US drug-compounding records, not a blanket claim about every research use or jurisdiction. Current FDA safety table.
Ipamorelin vs CJC-1295, Sermorelin and Tesamorelin
Ipamorelin
A five-residue GH secretagogue acting through GHS-R1a. Its individual studies do not require the presence of CJC-1295 to demonstrate a GH response.
GHRH analogues
CJC-1295, Sermorelin and Tesamorelin have different structures and evidence. Their individual findings cannot establish the effectiveness of an Ipamorelin blend.
For the identity and formulation distinctions, use the Ipamorelin vs CJC-1295 comparison or the CJC-1295 and Ipamorelin blend guide. For the other compounds’ own human evidence, see the Sermorelin guide and Tesamorelin guide.
“Works without CJC” has two meanings. Ipamorelin has demonstrated its own pharmacological activity. That does not establish a safe standalone regimen, nor prove that adding CJC improves a desired clinical outcome.
What can an Ipamorelin COA establish?
A laboratory report concerns a sample and specified tests. It does not establish the clinical benefits above. Read identity, quantity and method separately:
- Match the material and recordCheck the compound, salt or formulation description, sample identifier and report date. A similar product name does not prove a shipping-lot assignment.
- Separate identity from purityMass-spectrometry evidence can support molecular identity within the method’s scope. An HPLC area percentage concerns the assigned peak’s share of integrated detector signal, not automatically peptide mass per vial.
- Read the evidence typeA numeric result or modeled display is not an original instrument file. Check what the record actually supplies before describing chromatographic or spectral evidence.
- Keep biological claims separateA COA does not establish human safety, an effective dose, sterility unless tested, or treatment efficacy. Those are different questions requiring different evidence.
Use the worked guide to reading a peptide COA and the Lab Verified record library to examine the applicable report.
Ipamorelin research material
The Ipamorelin product page lists the current standalone material and available configurations. A separate blended product contains additional components; its combined labeled mass should not be treated as Ipamorelin alone. For related compound identities, use the GH-axis research overview.
For laboratory research only. Not for human or veterinary use. This guide summarizes published research and dated regulatory records; it does not provide an administration, cycle or treatment plan.
Frequently Asked Questions
What is Ipamorelin?
Ipamorelin is a synthetic five-residue peptide and growth hormone secretagogue. It activates the ghrelin receptor, GHS-R1a, and can stimulate release of the body's own growth hormone. It is not growth hormone itself or testosterone.
What are the proven benefits of Ipamorelin?
Human research demonstrates a short-term GH response, but the published randomized bowel-surgery trial did not show significant efficacy. The studies reviewed here do not establish human muscle growth, fat loss, improved sleep or long-term anti-aging benefits.
Does Ipamorelin reduce belly fat or build muscle?
Those effects are not established in the reviewed human evidence. GH release is not a substitute for measured body-composition or strength outcomes. One mouse study actually found increased adiposity, so fat loss should not be assumed from the mechanism.
Does Ipamorelin increase testosterone?
A reliable testosterone increase has not been established in the reviewed human studies. A 2024 study reported reproductive-axis changes in a species of fish; that does not demonstrate a testosterone benefit in people.
Can Ipamorelin work without CJC-1295?
Ipamorelin has demonstrated pharmacological activity when studied on its own. That does not establish a safe standalone regimen or prove that a CJC-1295 combination improves a desired clinical outcome. The compounds act through different receptor pathways.
What is the half-life of Ipamorelin?
A 1999 intravenous study in healthy male volunteers reported a terminal plasma half-life of about two hours. Its GH response peaked around 0.67 hours. Neither value establishes a personal dosing interval or the behavior of another formulation or route.
What is the downside of Ipamorelin?
Its long-term safety and many proposed benefits are not established. FDA has raised concerns about reported clinical adverse events, peptide impurities and aggregation. Two deaths occurred in treated surgical patients, but FDA states that a causal relationship to Ipamorelin is unclear.
Is it safe to take Ipamorelin every day?
The studies reviewed here do not establish a safe everyday regimen. Short intravenous studies cannot validate a personal schedule, repeated long-term use or a different product formulation. Research materials are not for human or veterinary use.
References
Primary publications are linked below. Trial registrations and FDA documents are linked beside the relevant findings. The September 8, 2026 search examined 54 exact-name PubMed records and three ClinicalTrials.gov entries. Abstracts were checked for every cited publication; available full reports and FDA’s detailed trial review were read for the relevant methods and results. A search finding is not a guarantee that every unpublished or differently indexed study has been found.
- Raun K et al. Ipamorelin, the first selective growth hormone secretagogue. European journal of endocrinology. 1998. PMID 9849822.
- Howard AD et al. A receptor in pituitary and hypothalamus that functions in growth hormone release. Science (New York, N.Y.). 1996. PMID 8688086.
- Kojima M et al. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature. 1999. PMID 10604470.
- Gobburu JV et al. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharmaceutical research. 1999. PMID 10496658.
- Johansen PB et al. Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. Growth hormone & IGF research : official journal of the Growth Hormone Research Society and the International IGF Research Society. 1999. PMID 10373343.
- Svensson J et al. The GH secretagogues ipamorelin and GH-releasing peptide-6 increase bone mineral content in adult female rats. The Journal of endocrinology. 2000. PMID 10828840.
- Andersen NB et al. The growth hormone secretagogue ipamorelin counteracts glucocorticoid-induced decrease in bone formation of adult rats. Growth hormone & IGF research : official journal of the Growth Hormone Research Society and the International IGF Research Society. 2001. PMID 11735244.
- Malmlöf K et al. Methylprednisolone does not inhibit the release of growth hormone after intravenous injection of a novel growth hormone secretagogue in rats. Growth hormone & IGF research : official journal of the Growth Hormone Research Society and the International IGF Research Society. 1999. PMID 10629165.
- Aagaard NK et al. Growth hormone and growth hormone secretagogue effects on nitrogen balance and urea synthesis in steroid treated rats. Growth hormone & IGF research : official journal of the Growth Hormone Research Society and the International IGF Research Society. 2009. PMID 19231263.
- Lall S et al. Growth hormone (GH)-independent stimulation of adiposity by GH secretagogues. Biochemical and biophysical research communications. 2001. PMID 11162489.
- Jiménez-Reina L et al. Influence of chronic treatment with the growth hormone secretagogue Ipamorelin, in young female rats: somatotroph response in vitro. Histology and histopathology. 2002. PMID 12168778.
- Venkova K et al. Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus. The Journal of pharmacology and experimental therapeutics. 2009. PMID 19289567.
- Greenwood-Van Meerveld B et al. Efficacy of ipamorelin, a ghrelin mimetic, on gastric dysmotility in a rodent model of postoperative ileus. Journal of experimental pharmacology. 2012. PMID 27186127.
- N Mohammadi E et al. Attenuation of Visceral and Somatic Nociception by Ghrelin Mimetics. Journal of experimental pharmacology. 2020. PMID 32801950.
- Johansen PB et al. Pharmacokinetic evaluation of ipamorelin and other peptidyl growth hormone secretagogues with emphasis on nasal absorption. Xenobiotica; the fate of foreign compounds in biological systems. 1998. PMID 9879640.
- Beck DE et al. 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. PMID 25331030.
- Lu Z et al. The growth hormone secretagogue receptor 1a agonists, anamorelin and ipamorelin, inhibit cisplatin-induced weight loss in ferrets: Anamorelin also exhibits anti-emetic effects via a central mechanism. Physiology & behavior. 2024. PMID 39043357.
- Gouda M et al. The influence of ghrelin agonist ipamorelin acetate on the hypothalamic-pituitary-testicular axis in a cichlid fish, Oreochromis mossambicus. Animal reproduction science. 2024. PMID 38996787.
- Semenistaya E et al. Determination of growth hormone releasing peptides metabolites in human urine after nasal administration of GHRP-1, GHRP-2, GHRP-6, Hexarelin, and Ipamorelin. Drug testing and analysis. 2015. PMID 25869809.
- Ferro P et al. Structure-activity relationship for peptídic growth hormone secretagogues. Drug testing and analysis. 2017. PMID 26811125.
