Pinc PeptideThe girly peptide research blog

Compare · updated 8 October 2026

Ipamorelin vs MK-677

The short answer

Both make the body release more of its own growth hormone by switching on the ghrelin receptor, the switch used by the ‘hunger hormone’ ghrelin, but MK-677 is a pill and not a peptide34. MK-677 has the bigger human record, and it is mixed: for up to a year it raised growth hormone and IGF-1, a growth factor that rises with growth hormone, but it did not slow Alzheimer’s disease, it raised blood sugar, and a hip-fracture trial was stopped early over a heart failure signal5678. Ipamorelin has far less human data, for benefits or harms: its published clinical studies gave it only by vein, for at most 7 days910. We found no study that compared the two in people or tested them together12.

At a glance

ComparedIpamorelinMK-677 (ibutamoren)
Evidence tierB At least one controlled human trialB At least one controlled human trial
Does it work?For fat loss, muscle and sleep: UntestedAn IV dose triggers a short burst of growth hormone9, but we found no study in people of fat loss, muscle or sleep311. Its only published patient trial, after bowel surgery, found no clear benefit10.For building muscle and lean mass: Mixed resultsIn older adults, a year of daily pills added about 1 kg of lean mass but did not improve strength or function5. In obese men, lean mass rose but body fat did not fall12.
FDANot approved for any use3Not approved for any use4
US pharmaciesPharmacies may not make it131415Pharmacies may not make it131416
SportBanned at all times1718Banned at all times1718
AustraliaPrescription only; illegal to hold without one19Prescription only; illegal to hold without one19
Half-lifeAbout 2 hours after an IV dose; none found for other routes9No human value found; a single dose acts for about 24 hours4
Taken asIntravenous infusion (the only route with published clinical data we found: healthy volunteers and surgery patients)
Subcutaneous injection (the usual clinic and gray-market route; we found no published human studies, only adverse-event reports)
Nasal spray (sold by compounders per FDA; about 20% absorbed in rats; one volunteer in an anti-doping study)
Oral tablets and troches (advertised by clinics per FDA’s 2024 review; no human data found)		By mouth as tablets, capsules or liquid (all human trials)
Injection (a 64 mg/mL product was seen for sale by FDA; no human data found)
What it isA lab-made chain of 5 amino acids, 3 of them building blocks not found in human proteins as such; it belongs to the growth-hormone-releasing peptide (GHRP) family3920.A lab-made small molecule, not a peptide, also called ibutamoren; its Merck developers found it works the same way as GHRP-6, a growth-hormone-releasing peptide421.
Effect on growth hormone in peopleOne IV dose (into a vein) in healthy men caused a single growth hormone burst that peaked at about 40 minutes and fell to very low levels within about 6 hours39.In 32 healthy adults aged 64 to 81, two weeks on the highest of three daily doses raised average 24-hour growth hormone by 97%, and IGF-1 reached the normal range for young adults by 4 weeks7.
Studied in people forGut recovery after bowel surgery, plus a study of blood levels and growth hormone response in 40 healthy men910.Body composition in healthy older adults, obesity, low bone density in older women, Alzheimer’s disease, hip-fracture recovery and, as LUM-201, children who make too little growth hormone568122223.
Largest and longest trials114 adults, for up to 7 days after bowel surgery10; a 320-patient trial finished in 2014 but has posted no results, and we found no publication of them1124.563 people with Alzheimer’s disease for 12 months, in whom it did not slow the disease, and a 2-year trial in healthy older adults, 65 of whom completed the first year58.
Biggest documented riskIn the surgery trial, low potassium was more common than on placebo (12.5% vs 3.4%), and 2 of 56 patients on it died; FDA says it is unclear whether the deaths were related310.Heart failure: a hip-fracture trial was stopped early after heart failure affected 4 patients (6.5%) on the drug vs 1 (1.7%) on placebo, and FDA cites it in listing MK-677 as a compounding safety risk4614.
Blood sugarHigh blood sugar at discharge was more common than on placebo after surgery (14.3% vs 8.6%), and FDA says there are not enough data to rule out glucose intolerance and diabetes3.Over a year in healthy older adults, fasting blood sugar rose by 0.3 mmol/L (5 mg/dL) and insulin sensitivity fell; in the Alzheimer’s trial, raised blood sugar was recorded in 15.4% on the drug vs 4.6% on placebo45.
AppetiteIn animal studies it raised food intake: in mice, along with body fat, and in rats after surgery2526.In the first year of a 2-year trial in older adults, increased appetite was reported by 29 of 43 people on it vs 8 of 22 on placebo, and it subsided within a few months45.
Cortisol, a stress hormoneDid not raise ACTH or cortisol in pigs, even at more than 200 times the dose that gave half its maximum growth hormone effect20.Did not change in a short study in older adults, but rose over a year of daily use57.
Lab tests of gray-market products52 of the latest 200 tests by Finnrick, an independent testing service, failed (11 December 2025 to 24 September 2026)27.Finnrick listed no MK-677 tests as of 25 September 2026; FDA’s lab found it, unlisted, in a children’s growth supplement in 20252829.

Does the growth hormone boost last?

In people, MK-677 kept IGF-1 raised: in the Alzheimer’s trial, IGF-1 was up 60.1% at 6 weeks and 72.9% at 12 months, although FDA’s review concludes from animal studies that the growth hormone response is likely to be lost with continuous dosing48. In rats given ipamorelin under the skin for 15 days, the growth hormone response to a test dose was slightly smaller afterward30. A higher hormone level is not the same as a health benefit: the same Alzheimer’s trial found no effect on the disease8.

Is there evidence for taking them together?

No: as of 7 October 2026, none of the 7 PubMed records that match ipamorelin and MK-677 (under any of its names) compared the two or gave them together to people, and ClinicalTrials.gov lists no trial of the pair12. So whether combining them adds any effect, or any risk, is unknown12.

Raised blood sugar was more common than on placebo in trials of each, so it is one known risk the two share34. In February 2026 the US Anti-Doping Agency announced a 3-year ban, starting in December 2025, for a masters weightlifter whose urine sample tested positive for ipamorelin and ibutamoren, MK-677’s other name31.

Ipamorelin is also sold in blends with other peptides, such as CJC-1295, sermorelin or tesamorelin33233. Our CJC-1295 vs ipamorelin comparison covers one of those pairings.

How have regulators acted on each?

On 29 October 2024, FDA’s compounding advisers voted 0-12, with 1 abstention, against letting pharmacies compound ipamorelin, and 1-13 against MK-677; for MK-677, several members raised fluid retention, heart failure and high blood sugar34.

MK-677 has been in Category 2, the group of compounding substances FDA says may present significant safety risks, since 29 September 2023 for pharmacies, because of possible heart failure1314. Ipamorelin appears on the same FDA page, which cites possible immune reactions, unnatural amino acids that make it harder to characterize, and serious adverse events, including death, in its IV surgery trial14. On 15 April 2026, HHS Secretary Robert F. Kennedy Jr. posted that FDA would remove 12 peptides from Category 2, ibutamoren among them, but FDA’s own pages still listed it there when checked on 5 October 2026131435.

FDA also says MK-677 does not qualify as a dietary supplement, and on 12 December 2025 it told an online seller that ‘for research use only’ statements did not stop its MK-677 products from being unapproved new drugs3637. On 24 August 2026, FDA sent warning letters to two online sellers of tesamorelin and ipamorelin blends, calling them unapproved new drugs3233.

Questions people ask

Is MK-677 better than ipamorelin?

Neither has been shown to increase strength or reduce body fat in people3512. MK-677 has much more human data, including a trial in which a year of it added lean mass but raised blood sugar in older adults, while ipamorelin’s published clinical studies lasted at most 7 days510. We found no study that compared the two in people12.

Can you take ipamorelin and MK-677 together?

We found no published or registered study of the pair, so whether it adds any effect or any risk is unknown12. Both raised blood sugar more often than placebo in trials, and a US weightlifter who tested positive for both accepted a 3-year ban, announced in February 20263431.

Which is better for sleep, MK-677 or ipamorelin?

Only MK-677 has been tested: in a small 1997 study, a week on the higher of two doses increased deep sleep by about 50% and REM sleep, the stage linked to dreaming, by more than 20% in 8 young adults compared with placebo38. We found no study of ipamorelin for sleep, and in its surgery trial insomnia was more common on it than on placebo (10.7% vs 5.2%)311.

Is MK-677 safer than ipamorelin?

MK-677 has more safety data, and that data includes raised blood sugar over a year and a hip-fracture trial stopped early over a heart failure signal56. Ipamorelin’s published human studies gave it by vein for at most 7 days, so the risks of longer use are unknown910.

Does MK-677 or ipamorelin cause water retention?

MK-677 can: in the first year of a 2-year trial in older adults, mild, short-lived leg swelling was reported in 19 of 43 people on it vs 6 of 22 on placebo, a difference that was not statistically significant, and several of FDA’s advisers raised fluid retention when the committee voted against allowing it in pharmacy compounding4534. For ipamorelin, FDA says it is concerned that the risks listed on growth hormone labels, including fluid retention, could also apply3.

Go deeper

Sources

  1. 1PubMed search: ipamorelin AND (ibutamoren OR MK-677 OR MK-0677 OR MK677) (7 results; none gave the two together to people) National Library of Medicine (PubMed), accessed 7 Oct 2026. pubmed.ncbi.nlm.nih.gov
  2. 2ClinicalTrials.gov search for ‘ipamorelin AND (ibutamoren OR MK-677 OR MK-0677 OR MK677)’ (0 studies) ClinicalTrials.gov, accessed 7 Oct 2026. clinicaltrials.gov
  3. 3FDA Briefing Document, Pharmacy Compounding Advisory Committee meeting of October 29, 2024: ipamorelin-related bulk drug substances (FDA evaluation dated 19 August 2024) U.S. Food and Drug Administration, 19 Aug 2024. fda.gov
  4. 4FDA Briefing Document, Pharmacy Compounding Advisory Committee meeting of October 29, 2024: ibutamoren mesylate (FDA evaluation dated 3 July 2024) U.S. Food and Drug Administration, 3 Jul 2024. fda.gov
  5. 5Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial Annals of Internal Medicine, 4 Nov 2008. pubmed.ncbi.nlm.nih.gov
  6. 6MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study Archives of Gerontology and Geriatrics, Sep 2011. pubmed.ncbi.nlm.nih.gov
  7. 7Stimulation of the growth hormone (GH)-insulin-like growth factor I axis by daily oral administration of a GH secretogogue (MK-677) in healthy elderly subjects The Journal of Clinical Endocrinology & Metabolism, Dec 1996. pubmed.ncbi.nlm.nih.gov
  8. 8Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial Neurology, 18 Nov 2008. pubmed.ncbi.nlm.nih.gov
  9. 9Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers Pharmaceutical Research, Sep 1999. pubmed.ncbi.nlm.nih.gov
  10. 10Prospective, 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, Dec 2014. pubmed.ncbi.nlm.nih.gov
  11. 11PubMed search: ipamorelin (54 results) National Library of Medicine (PubMed), accessed 8 Oct 2026. pubmed.ncbi.nlm.nih.gov
  12. 12Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure The Journal of Clinical Endocrinology & Metabolism, Feb 1998. pubmed.ncbi.nlm.nih.gov
  13. 13Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act (categories list) U.S. Food and Drug Administration, 14 May 2026. fda.gov
  14. 14Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks U.S. Food and Drug Administration, 22 Apr 2026. fda.gov
  15. 15Bulk Drug Substances Nominated for Use in Compounding Under Section 503B of the Federal Food, Drug, and Cosmetic Act (categories list) U.S. Food and Drug Administration, 21 Mar 2025. fda.gov
  16. 16Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act U.S. Food and Drug Administration, 14 May 2026. fda.gov
  17. 17World Anti-Doping Code International Standard: Prohibited List 2026 World Anti-Doping Agency, 24 Sep 2025. wada-ama.org
  18. 18World Anti-Doping Code International Standard: Prohibited List 2027 World Anti-Doping Agency, 21 Sep 2026. wada-ama.org
  19. 19Therapeutic Goods (Poisons Standard—October 2026) Instrument 2026 (F2026L01327) Federal Register of Legislation, Australian Government, 28 Sep 2026. legislation.gov.au
  20. 20Ipamorelin, the first selective growth hormone secretagogue European Journal of Endocrinology, Nov 1998. pubmed.ncbi.nlm.nih.gov
  21. 21Design and biological activities of L-163,191 (MK-0677): a potent, orally active growth hormone secretagogue Proceedings of the National Academy of Sciences, 18 Jul 1995. pubmed.ncbi.nlm.nih.gov
  22. 22Effect of alendronate and MK-677 (a growth hormone secretagogue), individually and in combination, on markers of bone turnover and bone mineral density in postmenopausal osteoporotic women The Journal of Clinical Endocrinology & Metabolism, Mar 2001. pubmed.ncbi.nlm.nih.gov
  23. 23Phase 2 Study of LUM-201 in Children With Growth Hormone Deficiency (OraGrowtH210 Trial) (NCT04614337) ClinicalTrials.gov, 17 Jun 2026. clinicaltrials.gov
  24. 24Safety and Efficacy of Ipamorelin Compared to Placebo for the Recovery of Gastrointestinal Function (NCT01280344) ClinicalTrials.gov, 13 Apr 2017. clinicaltrials.gov
  25. 25Growth hormone (GH)-independent stimulation of adiposity by GH secretagogues Biochemical and Biophysical Research Communications, 12 Jan 2001. pubmed.ncbi.nlm.nih.gov
  26. 26Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus Journal of Pharmacology and Experimental Therapeutics, Jun 2009. pubmed.ncbi.nlm.nih.gov
  27. 27Ipamorelin: safety testing results and vendor ratings Finnrick, 24 Sep 2026. finnrick.com
  28. 28Finnrick public data summary (llms-full.txt, generated 25 September 2026) Finnrick, 25 Sep 2026. finnrick.com
  29. 29Agebox iKids Growth Day Formula may be harmful due to hidden ingredient U.S. Food and Drug Administration, 23 Sep 2025. fda.gov
  30. 30Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats Growth Hormone & IGF Research, Apr 1999. pubmed.ncbi.nlm.nih.gov
  31. 31Weightlifting Athlete Accepts Sanction for Anti-Doping Rule Violations U.S. Anti-Doping Agency, 20 Feb 2026. usada.org
  32. 32Warning letter to Royal Peptides LLC (MARCS-CMS 734884) U.S. Food and Drug Administration, 24 Aug 2026. fda.gov
  33. 33Warning letter to NuScience Peptides LLC (MARCS-CMS 733652) U.S. Food and Drug Administration, 24 Aug 2026. fda.gov
  34. 34Final Summary Minutes of the Pharmacy Compounding Advisory Committee Meeting, October 29, 2024 U.S. Food and Drug Administration, 15 Jan 2025. fda.gov
  35. 35X post by HHS Secretary Robert F. Kennedy Jr. (@SecKennedy) on peptides removed from Category 2 X (formerly Twitter), 15 Apr 2026. x.com
  36. 36Warning letter to Agebox Inc. (MARCS-CMS 718252) U.S. Food and Drug Administration, 19 Dec 2025. fda.gov
  37. 37Warning letter to Dynamic Health Group dba SARMS America (MARCS-CMS 719257) U.S. Food and Drug Administration, 12 Dec 2025. fda.gov
  38. 38Prolonged oral treatment with MK-677, a novel growth hormone secretagogue, improves sleep quality in man Neuroendocrinology, Oct 1997. pubmed.ncbi.nlm.nih.gov

Not medical advice. Neither compound is recommended here. How we grade evidence · Report an error.