Ipamorelin Regret, Stopping, and Restarting: What Real Users and Clinical Data Actually Show

At a glance

• Approval / Not FDA-approved; no FDA-approved dose exists [1]
• Human data / Intravenous only: an ileus trial and a volunteer PK study [2][3]
• Subcutaneous use / FDA found no human PK, safety, or efficacy data [1]
• Half-life / About 2 hours after intravenous dosing [3]
• Main ileus result / 25.3 h vs 32.6 h to tolerate solid food; not significant (p=0.15) [2]
• Safety signals / More low potassium, insomnia, and high blood sugar at discharge than placebo [1][2]
• Regulatory / FDA category 2 for outsourcing compounding; WADA prohibited at all times [5][6]
• Dosing period in the ileus trial / Postoperative day 1 through day 7 or discharge [2]

What the human data cover

Ipamorelin is a five-amino-acid synthetic peptide that stimulates growth hormone release at the ghrelin/GH-secretagogue receptor, not the GHRH receptor [4][1]. It is not FDA-approved, has no US Pharmacopeia monograph, and was developed for postoperative ileus but reportedly discontinued after disappointing phase 2 results [1]. The human data are intravenous only: a phase 2 ileus trial using 0.03 mg/kg twice daily and a volunteer study using single 15-minute infusions [2][3]. FDA found no human pharmacokinetic, safety, or efficacy data for subcutaneous ipamorelin [1].

What the intravenous studies can and cannot tell you about stopping

In healthy male volunteers, intravenous ipamorelin had a terminal half-life of about 2 hours; growth hormone rose in a single sharp peak about 0.67 hours after the infusion and fell to negligible levels at every dose tested [3]. The ileus trial dosed patients twice daily from postoperative day 1 through day 7 or hospital discharge [2].

These are short-term intravenous studies in a laboratory or hospital setting. Their published abstracts report no outcomes on how people feel weeks after stopping, how often anyone regrets it, or whether a second course reproduces an earlier response [2][3]. Those questions have no answer from the human data.

Safety data from the ileus trial

In the ileus trial, 117 adults were enrolled and 114 analyzed; median time to tolerate solid food was 25.3 hours with ipamorelin vs 32.6 hours with placebo, not significant (p=0.15) [2]. Low potassium occurred in 12.5% vs 3.4%, insomnia in 10.7% vs 5.2%, and high blood sugar at discharge in 14.3% vs 8.6% [1][2]. Serious adverse events were 17.9% vs 15.5%, and two ipamorelin-treated patients died of surgical complications; FDA said the relationship is unclear but the deaths raise safety concerns [1][2]. FDA also states that GH/IGF-1 stimulation may carry approved growth hormone label risks, including neoplasm, glucose intolerance and diabetes, intracranial hypertension, fluid retention, hypothyroidism, and pancreatitis, and possibly QT prolongation; it found no data showing it would not [1].

Regulatory status

FDA lists ipamorelin acetate in category 2 as a bulk substance that raises significant safety risks for compounding by outsourcing facilities, added September 29, 2023 and still listed on FDA's page dated 04/22/2026 [5][7]. WADA names ipamorelin in S2.2.4, prohibited at all times in and out of competition on the 2026 and 2027 lists [6][8].

Frequently asked questions

›What happens when you stop ipamorelin?

No human study reports outcomes after stopping. In volunteers, intravenous ipamorelin had a half-life of about 2 hours, and growth hormone peaked at about 0.67 hours then fell to negligible levels [3]. The ileus trial dosed through day 7 or hospital discharge [2].

›Can you restart ipamorelin after a break?

No study tested restarting. Human dosing was intravenous: twice daily through day 7 or discharge in the ileus trial, and single 15-minute infusions in the volunteer study [2][3].

›Is ipamorelin FDA-approved?

No. Ipamorelin is not an FDA-approved drug and has no US Pharmacopeia monograph [1]. FDA lists ipamorelin acetate as a category 2 bulk substance that raises significant safety risks for compounding by outsourcing facilities [5][7].

›Did ipamorelin work in its main clinical trial?

The one published phase 2 trial did not show a significant difference on its key efficacy endpoint. Median time to tolerate a solid meal was 25.3 hours with ipamorelin and 32.6 hours with placebo, with p=0.15 [2]. Development was reportedly discontinued after disappointing phase 2 results [1].

References

1. U.S. Food and Drug Administration. U.S. Food and Drug Administration
2. Beck DE, Sweeney WB, McCarter MD, Ipamorelin 201 Study Group. 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(12):1527-34. Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients
3. Gobburu JV, Agersø H, Jusko WJ, Ynddal L. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res. 1999;16(9):1412-6. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers
4. Raun K, Hansen BS, Johansen NL, Thøgersen H, Madsen K, Ankersen M, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-61. Ipamorelin, the first selective growth hormone secretagogue
5. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks | FDA. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks | FDA
6. World Anti-Doping Agency. World Anti-Doping Agency
7. U.S. Food and Drug Administration. U.S. Food and Drug Administration
8. World Anti-Doping Agency. World Anti-Doping Agency