Ipamorelin: research, side effects and dosage in studies
In short
Ipamorelin is a five-amino-acid peptide that makes the pituitary gland release growth hormone [1]C. It has no marketing authorisation in the EU [6]regulator.
- Ipamorelin draws interest because it raises growth hormone: in healthy men growth hormone was released at every dose studied [2]B.
- The best human evidence is a phase 2 trial of 117 patients after bowel surgery. In it, ipamorelin did not differ significantly from placebo [3]A.
- We found no controlled human studies on muscle growth, fat loss or recovery.
- Ipamorelin is listed in Annex 1 A of Finland's medicines list, so it is controlled as a medicine, and Fimea names it in its warning about peptides bought online [7, 8]regulator. In sport it is prohibited at all times (WADA S2.2.4) [9]regulator.
What is ipamorelin?
Ipamorelin is a five-amino-acid peptide in the group of growth hormone-releasing peptides (GHRPs). It acts on the same receptor as GHRP-6 and makes the pituitary gland release growth hormone [1]C.
Ipamorelin was developed in the 1990s. The developers described it as the first substance in this group to release growth hormone selectively, that is, without raising other hormones the way the comparison substances did [1]C.
Ipamorelin has no marketing authorisation in the EU [6]regulator. According to Fimea, the label "for research use only" means the product is not intended for humans [7]regulator. Basics: What are peptides?. All substances: Peptides A-Z.
IGF-1 analogues, which have not been studied in humans, act on the same axis. Other growth hormone releasers of the same group on this site: GHRP-2 and hexarelin.
Evidence at a glance
Each cell gives the kind of study and its source. The letter is the evidence level, not the result.
| Claimed effect | Humans | Animals | Cells |
|---|---|---|---|
| Growth hormone rise | In healthy men (8 at each of five dose levels) growth hormone was released at every dose [2]B | Growth hormone rose in pigs [1]C | Released growth hormone from rat pituitary cells about as well as GHRP-6 [1]D |
| Other hormones (cortisol, ACTH, prolactin) | No controlled study; prolactin and cortisol rises reported in users of this group of substances [5] | In pigs ACTH and cortisol did not rise significantly, and FSH, LH, prolactin and TSH did not change [1]C | - |
| Bowel paralysis after surgery | 114 patients analysed, no significant difference from placebo [3]A | - | - |
| Muscle, fat, recovery | We found no controlled human study | - | - |
| Half-life | About 2 hours in healthy men [2]B | - | - |
| Safety | In a trial of up to 7 days, adverse events as common as with placebo [3]A; per the FDA, serious adverse events including a death with ipamorelin given into a vein [11]regulator; no long-term data [5] | - | - |
"-" = no such study is known.
What is ipamorelin studied for?
None of the ipamorelin uses below is approved [6]regulator. The only controlled human trial was on bowel paralysis after surgery, and it found no benefit [3]A.
- Bowel paralysis after surgery: a phase 2 trial in 117 adults after bowel surgery [3]A [4]E, not peer-reviewed. A second phase 2 trial of 320 patients was completed according to the registry, but no results are posted there and we found no publication [10]E, not peer-reviewed.
- Growth hormone release: animal and cell experiments [1]C and one study in healthy men [2]B.
Claims online. According to a 2026 review, peptides acting on the growth hormone axis are sold as "research compounds" without regulatory approval for physique or performance use [5]. We found no controlled human studies on muscle growth, fat loss or recovery.
How does ipamorelin work?
Ipamorelin binds the same receptor as GHRP-6 and makes the pituitary gland release growth hormone [1]C. In rat pituitary cells it released growth hormone about as effectively as GHRP-6 [1]D.
This receptor is also called the ghrelin receptor. Ipamorelin has been studied as a ghrelin receptor agonist, because ghrelin-like substances can speed up gut movement [3]A.
In healthy men growth hormone was released as a single burst, peaking at about 40 minutes [2]B.
Has ipamorelin been studied in humans?
A little: we found one pharmacokinetic study of ipamorelin in healthy men and one phase 2 trial of 117 patients that found no benefit [2]B [3]A.
Human studies
- Healthy men (1999). The study had five dose levels with eight men at each level. Ipamorelin released growth hormone at all doses, and its half-life was about 2 hours [2]B.
- Bowel paralysis after surgery (2014). A randomised, placebo-controlled phase 2 trial (NCT00672074) enrolled 117 adults, of whom 114 were analysed. Median time to the first tolerated meal was 25.3 hours with ipamorelin and 32.6 hours with placebo, but the difference was not statistically significant (p = 0.15). There were no significant differences in the key or secondary efficacy measures [3]A [4]E, not peer-reviewed.
- A second phase 2 trial. A trial of 320 patients (NCT01280344) was completed in May 2014 according to the registry, but no results are posted [10]E, not peer-reviewed.
The investigators note that the bowel paralysis trial was small and that patients had a broad range of underlying conditions [3]A. These are group-level trial results, and they do not transfer as such to a product bought online.
Promising, but only in animal and cell studies
This finding looks good, but it has not been tested in a controlled way in humans. Results from animal and cell studies cannot be transferred directly to humans.
-
Selective growth hormone release no human studies
In rat pituitary cells ipamorelin released growth hormone about as effectively as GHRP-6 [1]D. In pigs it did not raise ACTH or cortisol significantly, even at doses more than 200 times the dose giving half the growth hormone response. FSH, LH, prolactin and TSH levels did not change either [1]C.
If it held in humans: growth hormone could be raised without the stress hormone cortisol or other pituitary hormones rising at the same time.
Why it might not translate: the result comes from pigs and rat cells, and the experiments were done by the substance's developers [1]C. According to a 2026 review, users of peptides acting on the growth hormone axis have reported prolactin and cortisol rises, although the review covers the whole group of substances, not ipamorelin alone [5].
Evidence now: one publication from 1998 [1]. The known human studies measured growth hormone and bowel function, not selectivity [2]B [3]A.
Who studies ipamorelin?
The developers of ipamorelin published its animal and cell experiments in 1998 [1]C. The bowel paralysis trial was run by a group called the Ipamorelin 201 Study Group [3]A, and according to the registry the second phase 2 trial was sponsored by Helsinn Therapeutics [10]E, not peer-reviewed. We found no more recent human studies.
Author of this page: the editorial team
This page was written by the Molecular Recovery editorial team. The draft was made with the help of AI, and the claims were checked against the sources (AI policy). The page has not been medically reviewed. How we work: About us.
How long does ipamorelin stay in the body?
In healthy men ipamorelin had a half-life of about 2 hours when given as an infusion into a vein. The growth hormone peak came at about 40 minutes [2]B.
The person-to-person variation in growth hormone response was larger than the variation in blood ipamorelin levels, so the same dose does not give everyone the same response [2]B.
What side effects does ipamorelin have?
In the only published treatment trial, surgical inpatients received ipamorelin into a vein for up to a week, and adverse events overall were as common as with placebo [3]A. According to the FDA, however, a published study found serious adverse events, including death, with ipamorelin given into a vein [11]regulator. The FDA does not name the study. The only published trial we know of in which ipamorelin was given into a vein to improve gut function is the same trial in surgical patients [3]A. Its abstract does not mention deaths or whether their link to ipamorelin was assessed. There are no human studies of long-term use [5].
What users report. In the Reddit accounts we compiled (not research), 53 of 76 people (70%) reported some harm, most often: allergic reaction, hives or rash (13, 17%), injection site reaction (12, 16%), flushing or head rush after the shot (9, 12%) and sleep problems (9, 12%). People tend to post when something goes wrong, so this share does not tell how common harms are. Almost everyone used ipamorelin with other substances: 70 of 76 people (92%), most often with CJC-1295 (46). 13 (17%) described an allergic-type reaction, and 4 described their harm as severe. The harms in detail: Ipamorelin user experiences.
What the trials showed
In the phase 2 trial, any treatment-emergent adverse event occurred in 87.5% of the ipamorelin group and 94.8% of the placebo group. The investigators judged ipamorelin well tolerated at this dose for up to seven days [3]A. These were hospital patients after surgery, so the figures mainly describe the postoperative setting.
FDA assessment
The FDA has placed ipamorelin acetate in compounding category 2, citing among other things the serious harms with ipamorelin given into a vein described above. The FDA says products may carry a risk of immune reactions, and there are no safety data for certain other injection routes [11]regulator.
Harms reported for this group of substances
According to a 2026 review, users of peptides acting on the growth hormone axis have reported prolactin and cortisol rises, appetite changes, blood sugar disturbances, fluid retention, muscle and joint pain and injection-site reactions. The review covers the group of substances, not ipamorelin alone [5].
Risks in products
According to Fimea, there is no reliable information on the content, quality and safety of products sold as peptides. In injectables, impurities such as endotoxins can cause serious health harm [7]regulator. More: Side effects and safety.
Interactions and who has no data
We found no human studies of interactions with other medicines. The human studies included only healthy men and adult bowel surgery patients [2]B [3]A, so there are no data for pregnancy or breastfeeding, for children or for long-term use.
What speaks against it and what is unknown
The only published efficacy trial in humans found no benefit [3]A.
Contrary evidence
- In the phase 2 trial ipamorelin did not differ from placebo in the key or secondary efficacy measures [3]A.
- No results of the second phase 2 trial of 320 patients are posted in the registry [10]E, not peer-reviewed.
What the evidence does not support
- "Ipamorelin builds muscle and burns fat": we found no controlled human studies on this. The rise in growth hormone has been measured, but its effect on body composition has not been studied [2]B.
- "Ipamorelin does not raise other hormones": this was seen in pigs [1]C. Users of this group of substances have reported prolactin and cortisol rises [5].
- "Ipamorelin is safe for long-term use": the longest human trial lasted at most seven days [3]A, and there are no long-term safety data [5].
- "The vial always contains what the label says": according to Fimea there is no reliable information on the content of products sold as peptides [7]regulator.
Ipamorelin dosage in studies
There is no approved dosage, because ipamorelin has no marketing authorisation [6]regulator. Below are the doses used in published and registered human studies. In all of them the substance was given as an infusion into a vein under supervision.
| Study | Who | Dose and route | Duration |
|---|---|---|---|
| Healthy men (1999) | healthy men, 8 at each dose level | 4.21 to 140.45 nmol/kg, 15-minute infusion into a vein, five dose levels | single dose [2]B |
| Bowel paralysis, NCT00672074 (2014) | 117 adults after bowel surgery | 0.03 mg/kg into a vein twice a day | postoperative days 1-7 or until discharge [3]A |
| Bowel function, NCT01280344 | 320 patients after bowel surgery | 0.03 or 0.06 mg/kg twice a day or 0.06 mg/kg three times a day into a vein | no results posted [10]E, not peer-reviewed |
What the numbers do not tell you. The doses were given into a vein in hospital or study conditions, and they are not recommendations. The first study gives the dose in nanomoles per kilogram of body weight and the second in milligrams per kilogram [2]B [3]A. More detail: Ipamorelin doses in studies and the calculator. Doses of other substances: Dosing.
Is ipamorelin legal in Finland?
Ipamorelin is listed in Annex 1 A of Fimea's medicines list [8]regulator. Annex 1 A substances are controlled as medicines in Finland and are always treated like prescription-only medicines. Ipamorelin has no marketing authorisation [6]regulator.
- Medicines list. Ipamorelin is named in annex 1 A of the Finnish medicines list (Fimea decision 230/2025), which lists medicinal substance analogues and prohormones classified as medicines [8]regulator.
- Marketing authorisation. Ipamorelin does not appear in the EMA medicines data file generated on 15 Sep 2026 [6]regulator.
- Fimea warning of 29 June 2026. Fimea's warning about injectable peptides bought online names ipamorelin alongside BPC-157, TB-500 and CJC-1295 [7]regulator.
- Import. Ordering medicines from outside the EU is covered on the page Peptides and the law in Finland. Bringing them back from travel: Travelling with peptides.
This is not legal advice. Disclaimer.
Is ipamorelin a doping substance?
Yes. On the WADA 2026 prohibited list, ipamorelin is named among growth hormone releasing factors (S2.2.4). Substances in this class are prohibited at all times, in and out of competition [9]regulator.
How is an ipamorelin product assessed?
You cannot be sure what a product contains. According to Fimea, the label "for research use only" means the product is not intended for humans, and there is no reliable information on the content, quality and safety of products sold as peptides [7]regulator. A 2026 review also stresses uncertainty about product composition and dose in unregulated supply chains [5].
A seller's own certificate of analysis (COA) does not prove a product pure or safe by itself. For a certificate even to describe the content, it would have to identify the substance by mass spectrometry (MS), state the amount and purity (HPLC) and cover the same batch as the vial. More: How to read a COA and check a test result. Handling: Mixing and handling.
FAQ
Is ipamorelin an approved medicine?
No. It has no marketing authorisation in the EU [6]regulator.
Does ipamorelin raise growth hormone?
Yes. In healthy male volunteers it released growth hormone at all doses studied [2]B.
Does ipamorelin build muscle?
Not known. We found no controlled human studies on this. The only published phase 2 trial was on bowel paralysis and found no benefit [3]A.
What side effects does ipamorelin have?
In the only published treatment trial, adverse events overall were as common as with placebo [3]A, but according to the FDA a published study found serious adverse events, including death, with ipamorelin given into a vein [11]regulator. There are no human studies of long-term harms, and according to a review, users of this group of substances have reported rises in prolactin and cortisol, for example [5].
Is there a dose of ipamorelin studied in humans?
Only study doses given into a vein in study conditions, no approved dosage: Ipamorelin dosage in studies. The figures are not recommendations [2]B [3]A.
Is ipamorelin banned in sport?
Yes. It is named on the WADA 2026 prohibited list in class S2.2.4 and is banned at all times [9]regulator.
Is ipamorelin legal in Finland?
It is listed in Annex 1 A of Fimea's medicines list, so in Finland it is controlled as a medicine and always treated like a prescription-only medicine [8]regulator. Fimea's 29 June 2026 warning on injectable peptides names it [7]regulator. This is not legal advice.
What do users themselves report about ipamorelin?
In the Reddit accounts of 76 people we compiled (not research), 31 (41%) reported some benefit and 53 (70%) some harm. The accounts are self-selected and prove neither that it works nor that it is safe: Ipamorelin user experiences.
Read the research yourself: sources
Every source opens the original publication or the regulator's page. The level shows what the source itself reports.
- Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139:552-561. PMID 9849822 C
- Gobburu JV, et al. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res. 1999;16:1412-1416. PMID 10496658 B
- 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. Int J Colorectal Dis. 2014;29:1527-1534. PMID 25331030 A
- ClinicalTrials.gov. NCT00672074: Phase II study of ipamorelin compared to placebo for post-operative ileus (completed, 117 participants). ClinicalTrials.gov E, not peer-reviewed
- Dominikowski A, et al. The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration. Front Endocrinol (Lausanne). 2026;17:1822475. PMID 42395176 (review)
- European Medicines Agency. Medicine data (human medicines, data set of 15 Sep 2026): ipamorelin not listed. EMA regulator
- Fimea. Fimea varoittaa: älä käytä verkosta ostettuja pistettäviä peptidejä / Fimea warns: do not use injectable peptides purchased online. 29 Jun 2026. Fimea regulator
- Finland. Lääkeluettelo (Fimea medicines list), 230/2025, annex 1 A. Finlex regulator
- World Anti-Doping Agency. Prohibited List 2026, section S2.2.4. WADA regulator
- ClinicalTrials.gov. NCT01280344: Safety and Efficacy of Ipamorelin Compared to Placebo for the Recovery of Gastrointestinal Function (phase 2, sponsor Helsinn Therapeutics, randomised, 320 participants, completed May 2014, no results posted). Registry record, not peer-reviewed. ClinicalTrials.gov E, not peer-reviewed
- U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks, category 2 entry "Ipamorelin acetate" (503B, 29 Sep 2023; content current as of 22 Apr 2026). FDA regulator
Research sources checked 9-13 Oct 2026. Regulator and registry sources checked 15 Sep to 13 Oct 2026.
Evidence levels: A = randomised human trial or meta-analysis · B = observational human study or case series · C = animal study · D = cell or laboratory study · E = not peer-reviewed · regulator = a regulator's assessment or decision, not research evidence. The marker official means official product information (summary of product characteristics or label); it is not research evidence. For a review, the level shows what kind of research the statement rests on. No level: statements that something has not been studied, reviews' interpretations, named hypotheses and the general rules in our certificate-of-analysis guide.
Content is general information about research, not medical advice. If you have symptoms, contact a healthcare professional.