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Ingredients

Ibutamoren (MK-677)

Ibutamoren · MK-677 · MK-0677 · Ibutamoren mesylate

Snapshot

IndicationsContraindications
  • Fat-free mass in obesity1
  • Diet-induced catabolism2
  • Sleep quality3
  • Bone turnover markers4, 5
  • Growth hormone deficiency6, 7
  • IGF-1 in hemodialysis8
  • Heart failure risk9
  • Diabetes10
  • Hypertension10
  • Under 18 years10

Ibutamoren (MK-677) is an orally active growth hormone secretagogue that acts as a ghrelin receptor agonist, raising growth hormone (GH) and insulin-like growth factor 1 (IGF-1)11. The Food and Drug Administration (FDA) places ibutamoren mesylate in its compounding category for significant safety risks, citing potential congestive heart failure9. The World Anti-Doping Agency (WADA) prohibits it at all times9. People take it to raise growth hormone and for sleep; in a small trial, bedtime dosing increased deep and REM sleep in healthy young and older adults3. Recreationally active adults seeking body composition changes are the typical users.

GH and IGF-1 rise consistently in trials, but clinical outcomes have not followed.12 A 12-month trial in Alzheimer disease found no slowing of progression12. A hip fracture trial showed little functional gain and ended early for a heart failure signal13. A case report describes reversible liver injury after two months' use.14 A 2025 case report described liver enzyme elevation in a healthy man after two months of use, resolving on stopping. Products are sold as capsules, often marketed as selective androgen receptor modulators; see Form comparison.

The most consequential caution is fluid retention and heart failure in older, medically fragile patients, with worsened glucose handling across trials. The FDA's review also names hyperglycemia and liver enzyme elevations as serious concerns15.

Last updated October 17, 2026. Read how we make monographs.

In the full monograph

42 sources, 29 studies

  • When to useThe situations practitioners use it for, each with the reason and the study behind it.
  • SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
  • Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
  • How it worksWhat it is and how it works in the body, in plain terms.
  • Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
  • Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
  • Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.
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Sources

  1. 1Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure.pubmed.ncbi.nlm.nih.govSvensson, Lönn, Jansson et al. · The Journal of clinical endocrinology and metabolism · 1998 · Pubmed
  2. 2MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism.pubmed.ncbi.nlm.nih.govMurphy, Plunkett, Gertz et al. · The Journal of clinical endocrinology and metabolism · 1998 · Pubmed
  3. 3Prolonged oral treatment with MK-677, a novel growth hormone secretagogue, improves sleep quality in man.pubmed.ncbi.nlm.nih.govCopinschi, Leproult, Van Onderbergen et al. · Neuroendocrinology · 1997 · Pubmed
  4. 4Effect 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.pubmed.ncbi.nlm.nih.govMurphy, Weiss, McClung et al. · The Journal of clinical endocrinology and metabolism · 2001 · Pubmed
  5. 5Oral administration of the growth hormone secretagogue MK-677 increases markers of bone turnover in healthy and functionally impaired elderly adults. The MK-677 Study Group.pubmed.ncbi.nlm.nih.govMurphy, Bach, Plotkin et al. · Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research · 1999 · Pubmed
  6. 6Oral administration of growth hormone (GH) releasing peptide-mimetic MK-677 stimulates the GH/insulin-like growth factor-I axis in selected GH-deficient adults.pubmed.ncbi.nlm.nih.govChapman, Pescovitz, Murphy et al. · The Journal of clinical endocrinology and metabolism · 1997 · Pubmed
  7. 7Effects of oral administration of ibutamoren mesylate, a nonpeptide growth hormone secretagogue, on the growth hormone-insulin-like growth factor I axis in growth hormone-deficient children.pubmed.ncbi.nlm.nih.govCodner, Cassorla, Tiulpakov et al. · Clinical pharmacology and therapeutics · 2001 · Pubmed
  8. 8Oral ghrelin receptor agonist MK-0677 increases serum insulin-like growth factor 1 in hemodialysis patients: a randomized blinded study.pubmed.ncbi.nlm.nih.govCampbell, Patrie, Gaylinn et al. · Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association · 2018 · Pubmed
  9. 9US statusfda.govWhat the FDA (its lists of substances nominated for pharmacy compounding, and Drugs@FDA) and the World Anti-Doping Agency's Prohibited List say about this ingredient, in their own words. A legal status, not evidence of benefit or harm
  10. 10US product labelsdsld.od.nih.govWarnings printed on US dietary supplement labels with this ingredient, from the NIH Office of Dietary Supplements' Dietary Supplement Label Database (DSLD). Manufacturers' precautions, not evidence of harm
  11. 11Stimulation 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.pubmed.ncbi.nlm.nih.govChapman, Bach, Van Cauter et al. · The Journal of clinical endocrinology and metabolism · 1996 · Pubmed
  12. 12Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial.pubmed.ncbi.nlm.nih.govSevigny, Ryan, van Dyck et al. · Neurology · 2008 · Pubmed
  13. 13MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study.pubmed.ncbi.nlm.nih.govAdunsky, Chandler, Heyden et al. · Archives of gerontology and geriatrics · 2011 · Pubmed
  14. 14Hepatotoxicity induced by MK-677.pubmed.ncbi.nlm.nih.govCobani, Amin, Hasso et al. · BMJ case reports · 2025 · Pubmed
  15. 15FDA actionsfda.govFDA warning letters, import alerts and Pharmacy Compounding Advisory Committee documents that name this ingredient, in the FDA's words. Findings about products sold and a regulator's review, not evidence of harm from the ingredient itself