MK-677 (ibutamoren): research, side effects and dosage in studies

In short

MK-677, or ibutamoren, is not a peptide but a compound taken by mouth that raises growth hormone. It has been studied in randomised human trials [1]A, but it has no marketing authorisation as a medicine [9]regulator.

• In older adults MK-677 increased fat-free mass over a year, but strength and function did not improve [2]A.
• In trials blood sugar rose and insulin sensitivity fell [2, 5]A.
• A trial in hip fracture patients was stopped because of a heart failure safety signal [3]A.
• In products bought online the content did not always match the label, and ibutamoren has also been found in products sold as other substances [12]D.
• In Finland ibutamoren is in Annex 1 of the medicines list, so it is controlled as a medicine [10]regulator, and in sport it is prohibited at all times (WADA S2.2.4) [11]regulator.

What is MK-677?

MK-677, or ibutamoren (ibutamoren mesylate, also MK-0677), is not a peptide. It is a non-peptide compound taken by mouth that mimics growth hormone-releasing peptides [1]A [8]regulator.

According to EMA, ibutamoren acts similarly to GHRP-6 and increases the body's own growth hormone production [8]regulator. Researchers describe it as an oral ghrelin mimetic [2]A.

MK-677 is on this site because it is sold and discussed alongside peptides. In products bought online it has also been found in packages sold as another substance [12]D. Basics: What are peptides?. All substances: Peptides A-Z.

Evidence at a glance

Each cell gives the kind of study and its source. The letter is the evidence level, not the result.

"-" = no such study is known.

What is MK-677 studied for?

None of the uses below is approved: MK-677 has no marketing authorisation in the EU [9, 16]regulator. In humans it has been studied in several placebo-controlled trials [1, 2, 3, 4, 5, 6]A.

• Ageing and body composition: a two-year trial in healthy people aged 60 to 81 [2]A.
• Obesity: an eight-week trial in obese men [5]A.
• Recovery from hip fracture: two trials in older patients [3, 4]A.
• Alzheimer's disease: a one-year trial in 563 patients [6]A.
• Protein breakdown on restricted food intake: a one-week study in eight healthy people [1]A.
• Growth hormone deficiency: in 2017 the European Commission granted ibutamoren mesylate an orphan designation for this use. A designation is not a marketing authorisation [8]regulator.

Claims online. The claim that MK-677 builds muscle and strength rests partly on real results: fat-free mass increased [2, 5]A. Strength and function, however, did not improve in older adults [2]A.

How does MK-677 work?

MK-677 makes the body release its own growth hormone. According to researchers it mimics ghrelin and activates the growth hormone secretagogue receptor. Ghrelin is a hormone made by the body that stimulates growth hormone release [2]A.

In older adults MK-677 raised growth hormone and IGF-1 to the levels of young adults [2]A, and in obese men IGF-1 rose by about 40% [5]A. Cortisol rose as well [2]A.

Has MK-677 been studied in humans?

Yes, in several randomised, placebo-controlled human trials [1, 2, 3, 4, 5, 6]A. The results are mixed: lab values changed, but physical function hardly improved.

The main trials

• Healthy older adults (2008). In a two-year trial, 65 healthy people aged 60 to 81 received MK-677 or placebo. Fat-free mass increased by 1.1 kg over a year, while it fell by 0.5 kg with placebo. Visceral fat and total fat mass did not change differently, but limb fat increased and weight rose by 2.7 kg. Strength and function did not improve [2]A.
• Obese men (1998). In an eight-week trial, 24 obese men aged 18 to 50 received MK-677 or placebo. IGF-1 rose by about 40% and fat-free mass increased, but total fat mass and visceral fat did not change significantly [5]A.
• Hip fracture (2004 and 2011). Six months of treatment raised IGF-1 by 84%, but there were no significant differences from placebo in measures of physical function [4]A. In another trial of 123 patients, walking speed improved but most other measures did not, and the trial was stopped because of a heart failure safety signal [3]A.
• Alzheimer's disease (2008). In a one-year trial of 563 patients, MK-677 raised IGF-1 but did not slow the progression of the disease [6]A.
• Restricted food intake (1998). In eight healthy volunteers on restricted energy intake, MK-677 reversed the negative nitrogen balance, a sign of protein breakdown, within a week [1]A.

These are group-level results. An individual's result can differ, and the results do not transfer as such to a product bought online, whose content does not always match its label [12]D.

Who studies MK-677?

The human efficacy trials covered on this page were published between 1998 and 2011 [1, 2, 3, 4, 5, 6]A. Newer publications are mostly laboratory analyses of products bought online or seized [12, 13]D and one case report of a harm [14]B. In Europe, ibutamoren mesylate received an orphan designation in 2017 [8]regulator.

Author of this page: 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.

What side effects does MK-677 have?

MK-677 trials found increased appetite, swelling, muscle pain, a rise in blood sugar and reduced insulin sensitivity [2]A. The most serious finding is a heart failure safety signal in hip fracture patients [3]A.

What users report. In the Reddit accounts we compiled (not research), 50 of 80 people (63%) reported some harm, most often: higher blood sugar or insulin resistance (12, 15%), strong hunger (unwanted) (11, 14%) and nausea or stomach upset (7, 9%). People tend to post when something goes wrong, so this share does not tell how common harms are. MK-677 is taken by mouth, and only 8 of 80 people (10%) used other substances at the same time, so the accounts describe this substance more clearly than most other summaries. 63 of 87 accounts came from the users' own forum r/mk677. The harms in detail: MK-677 user experiences.

Blood sugar and hormones

In the two-year study in older adults, fasting glucose rose by 0.3 mmol/l on average and insulin sensitivity fell. HbA1c, a measure of long-term blood sugar control, rose by 0.2 percentage points. The most common harms were increased appetite, which settled within a few months, and transient mild swelling of the lower legs and muscle pain. Cortisol rose [2]A.

In obese men, the oral glucose tolerance test worsened after two and eight weeks of treatment, although fasting glucose did not change [5]A.

Heart

The trial in hip fracture patients was stopped because a safety signal suggesting heart failure appeared in a limited number of patients. The authors concluded that the substance had an unfavourable safety profile in this patient group [3]A. According to the FDA, ibutamoren poses significant safety risks because of the potential for heart failure in certain patients [7]regulator.

Liver

In a case report, an otherwise healthy man in his early 30s developed raised liver enzymes after two months of MK-677 use, and the values returned to normal after he stopped. This is a single case [14]B.

More: Side effects and safety.

Interactions and who has no data

Interactions with other medicines have not been studied. Because MK-677 raised blood sugar and reduced insulin sensitivity [2, 5]A, there are no data on use together with medicines that affect blood sugar. There are no data for pregnancy or breastfeeding. In hip fracture patients the safety profile was unfavourable [3]A.

What speaks against it and what is not known

The main evidence against is that changes in lab values did not show up in physical function, and harms appeared already during the trials [2, 3]A.

Evidence against

• In older adults strength and function did not improve, although fat-free mass increased [2]A.
• In hip fracture patients most measures of physical function did not improve [3, 4]A.
• The progression of Alzheimer's disease did not slow [6]A.
• Total fat mass and visceral fat did not fall compared with placebo [2, 5]A.

What the evidence does not support

• "MK-677 is a peptide": it is not. It is a non-peptide compound taken by mouth [1]A.
• "MK-677 builds muscle and strength": fat-free mass increased [2, 5]A, but in older adults strength and function did not improve [2]A.
• "Taken by mouth, it is safer than an injection": the route does not make it safe. Blood sugar rose and insulin sensitivity fell [2, 5]A, and the FDA considers the substance a significant safety risk [7]regulator.
• "MK-677 is an ordinary food supplement": ibutamoren is in Annex 1 of the Finnish medicines list and is controlled as a medicine [10]regulator. Some seized products were presented as food supplements even though they contained unapproved drug substances [13]D.

What is not known

• Whether MK-677 improves physical function: the size and length of the study in older adults were insufficient to assess functional outcomes [2]A.
• Who is at risk of heart failure: in the hip fracture trial the signal involved a limited number of patients [3]A, and the FDA refers to a risk in certain patients [7]regulator.
• Long-term effects on blood sugar: the longest trial lasted two years, and even there fasting glucose rose and insulin sensitivity fell [2]A.

MK-677 dosage in studies

There is no approved dosage, because MK-677 has no marketing authorisation [9, 16]regulator. The adult trials covered here that state a dose used 25 mg once a day [1, 2, 3, 5, 6]A.

In the study in older adults, the dose of four participants was lowered to 10 mg because of a rise in blood sugar or joint pain [2]A.

What the numbers do not tell you. These are amounts used in studies, not instructions or recommendations. In the trials the substance was given under supervision, and harms still appeared [2, 3]A. A wider table of study doses: MK-677 doses in studies. Why the vial calculator does not cover this substance: MK-677 and the calculator.

Situation in the United States

In the United States, the FDA has placed ibutamoren mesylate in compounding category 2 (503A on 29 Sep 2023 and 503B on 29 Dec 2022) because of the potential risk of heart failure [7]regulator. Drugs@FDA listed no approved ibutamoren product on 12 Oct 2026 [15]regulator.

Is MK-677 legal in Finland?

MK-677 has no marketing authorisation [9, 16]regulator. Ibutamoren is listed in Annex 1 of Fimea's medicines list, and Annex 1 substances are controlled as medicines in Finland [10]regulator.

• Medicines list. Ibutamoren is listed in Annex 1 of the Finnish medicines list (Fimea decision 230/2025). Under the decision, Annex 1 substances are controlled as medicines [10]regulator.
• Marketing authorisation. On 12 Oct 2026 the EMA data on centrally authorised medicines contained no medicine with ibutamoren [9]regulator, and the EMA Article 57 database had no ibutamoren product in any EU or EEA country (data as of 21 Sep 2026) [16]regulator.
• Orphan designation. In the EU, ibutamoren has an orphan designation for growth hormone deficiency, but a designation is not a marketing authorisation [8]regulator.
• Import. Ordering medicines from outside the EU is covered on Peptides and the law in Finland. Bringing them back from a trip: Travelling with peptides.

This is not legal advice. Disclaimer.

Is MK-677 doping?

Yes. On the WADA 2026 Prohibited List, ibutamoren (MK-677) is named among growth hormone secretagogues (S2.2.4). Substances in this class are prohibited at all times, including out of competition [11]regulator.

In a survey by European official medicines laboratories of suspected illegal medicines bought as sport performance enhancers, ibutamoren was among the five most common substances [13]D.

How is an MK-677 product assessed?

You cannot be sure what a product contains. In a US analysis, 44 products sold online as SARMs were bought. Of these, 17 contained another unapproved drug, such as ibutamoren, 11 contained substances not listed on the label, and in only 18 did the amount match the label [12]D.

In a five-year survey by European official medicines laboratories, 324 samples from 13 countries, mostly from illegal sources, were analysed. 24% of the products were presented as food supplements. According to the researchers, the limited quantitative data suggest that most samples contained an active amount of substance and some even too much [13]D.

Because the label does not always match the content [12]D, a seller's own certificate of analysis (COA) does not by itself show what a product contains, nor does it show the product is safe. More: How to read a COA and check a test result.

FAQ

Read the research yourself: sources

Every source opens the original publication or the regulator's page. The level shows what the source itself reports.

1. Murphy MG, et al. MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism. J Clin Endocrinol Metab. 1998;83:320-325. PMID 9467534 A
2. Nass R, et al. Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial. Ann Intern Med. 2008;149:601-611. PMID 18981485 A
3. Adunsky A, et al. MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study. Arch Gerontol Geriatr. 2011;53:183-189. PMID 21067829 A
4. Bach MA, et al. The effects of MK-0677, an oral growth hormone secretagogue, in patients with hip fracture. J Am Geriatr Soc. 2004;52:516-523. PMID 15066065 A
5. Svensson J, et al. Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure. J Clin Endocrinol Metab. 1998;83:362-369. PMID 9467542 A
6. Sevigny JJ, et al. Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial. Neurology. 2008;71:1702-1708. PMID 19015485 A
7. U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks, category 2 entry "Ibutamoren mesylate" (content current as of 22 Apr 2026). FDA regulator
8. European Medicines Agency. EU/3/17/1882: orphan designation for treatment of growth hormone deficiency (ibutamoren mesilate), designated 20 Jun 2017, status positive. EMA regulator
9. European Medicines Agency. Medicine data (data set of 12 Oct 2026): no product with ibutamoren. EMA regulator
10. Finland. Lääkeluettelo (Fimea medicines list), 230/2025, section 2 and annex 1 ("Ibutamoreeni"). Finlex regulator
11. World Anti-Doping Agency. 2026 Prohibited List, S2.2.4 Growth hormone releasing factors (growth hormone secretagogues and their mimetics). WADA regulator
12. Van Wagoner RM, et al. Chemical Composition and Labeling of Substances Marketed as Selective Androgen Receptor Modulators and Sold via the Internet. JAMA. 2017;318:2004-2010. PMID 29183075 D
13. Barrios MM, et al. SARMs, Metabolic Modulators and Growth Hormone Secretagogues in Suspected Illegal Medicines, Bought as Sport Performance Enhancers: A Retro- and Prospective Study Within the GEON. Drug Test Anal. 2025;17:2078-2085. PMID 40551438 D
14. Cobani E, et al. Hepatotoxicity induced by MK-677. BMJ Case Rep. 2025;18:e265728. PMID 40675653 B
15. U.S. Food and Drug Administration. Drugs@FDA: FDA-approved drugs database, as of 12 Oct 2026: no product with ibutamoren. FDA regulator
16. European Medicines Agency. Article 57 product data (EMA/518502/2018 Rev.89, data as of 21 Sep 2026): no product with ibutamoren in any EU/EEA country. EMA regulator

Sources checked 12 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.