MK-677 Side Effects Reported in Published Research

MK-677, also called ibutamoren, is a lab-made compound that is taken by mouth and raises growth hormone. People search for MK-677 side effects because it is talked about online for muscle and body composition. This guide explains what MK-677 is, how it works, what published trials report on its uses, doses, and side effects, and what is still unknown. It describes research only and is not advice for any person. For a closer look at the upside findings, see the MK-677 benefits research guide.

What Is MK-677?

Ghrelin is often called the hunger hormone. Besides hunger, it also tells the pituitary gland to release growth hormone. According to Wikipedia, MK-677 copies ghrelin by switching on the ghrelin receptor. It raises growth hormone and IGF-1, a growth signal made mostly by the liver, and it also raises cortisol, the body’s stress hormone.

MK-677 has never been approved as a medicine. Wikipedia describes it as an investigational drug and says it is banned in most sports. It has been tested in clinical trials, mostly in older adults and in people with specific medical conditions.

Is MK-677 a Peptide?

No. A peptide is a short chain of amino acids, the building blocks of proteins. Wikipedia calls MK-677 a non-peptide molecule, and a 2018 review in Sexual Medicine Reviews calls it an orally available small-molecule drug.

It is grouped with peptides online because it does a similar job. Like ipamorelin and sermorelin, it prompts the body to release its own growth hormone. A 1996 trial describes it as a mimic of a growth hormone-releasing peptide. Because it is a small molecule, the trials gave it by mouth once a day.

MK-677 Benefits and Uses in Research

The table shows what MK-677 has been tested for and how much evidence backs each use.

Use	Status	What the research says
Raising growth hormone and IGF-1	Shown in trials	In the 2008 trial of healthy older adults, both rose to young-adult levels.
Fat-free mass	Shown, with limits	It rose by about 1.1 kg, compared with a small loss on placebo, but strength and function did not change.
Recovery after hip fracture	Tested, not shown	A 2004 trial found no significant gain in function. A 2011 trial was stopped early over a heart failure signal.
Bone health	Mixed	Bone turnover markers rose. In women with osteoporosis, adding it to alendronate raised hip bone density more (4.2 percent vs 2.5 percent), but not at other sites.
Protein loss while dieting	Early finding	In a 1998 study of 8 healthy volunteers on restricted calories, it improved their nitrogen balance over 7 days.
Alzheimer disease	Tested, no effect	In 563 patients over 12 months, it raised IGF-1 but did not slow the disease.
Muscle building in healthy adults	Promoted online, not proven	A 2026 review says claimed benefits for performance and recovery remain unsubstantiated by human trials.

MK-677 reliably raises growth hormone in the studies reviewed here. Whether that translates into better strength, recovery, or health has not been shown.

How MK-677 Works

Think of the body’s growth hormone release as a tap with a brake. The brain sends a start signal, a second hormone acts as a brake, and the pituitary gland releases growth hormone in bursts. A 1998 review says compounds like MK-677 act as functional somatostatin antagonists, which means they ease the body’s own brake and boost the start signal.

The 1996 trial found that MK-677 made the existing bursts taller without adding more of them. Growth hormone then tells the liver to make IGF-1, which helps tissues grow and repair. The 2018 review notes that compounds in this class keep the body’s natural feedback loop, which may limit how high growth hormone climbs.

MK-677 Dosage in Published Research

There is no approved dose of MK-677, and this guide does not recommend one. What can be said is what supervised trials used. They gave it by mouth, once a day.

The 1996 trial in 32 older adults tested 2, 10, and 25 mg a day, and growth hormone rose in step with the amount. The 2008 two-year trial, the 2011 hip fracture trial, and the Alzheimer trial all used 25 mg a day. These are fixed amounts from trials in specific groups, not advice for any person. Exact amounts on retail, clinic, and telehealth sites do not come from trials in healthy adults, so this guide does not repeat them.

Because MK-677 is taken by mouth, the trials had no mixing or injection steps. Research material still follows the supplier’s handling sheet. The MK-677 dosage research guide covers what the papers report about amounts.

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MK-677 Side Effects and Safety

The record comes from supervised trials and from reports of misuse. It is not a prediction for any person.

Appetite and swelling. The most common effects in the 2008 trial were increased appetite that faded over a few months, and mild leg swelling and muscle pain that came and went. The appetite effect fits the way it works, since it copies the hunger hormone.
Weight. Body weight rose by 2.7 kg on MK-677 and 0.8 kg on placebo. Fat-free mass includes water as well as muscle, and limb fat rose more on MK-677 than on placebo. So the gain was not simply muscle.
Blood sugar. Fasting glucose rose in the 2008 trial and insulin sensitivity decreased. A 1996 trial reported a rise from 5.4 to 6.8 mmol/L after 4 weeks. A 1998 trial in obese men found impaired sugar handling on a glucose tolerance test.
Heart. The 2011 hip fracture trial ended early because of a signal of congestive heart failure, and the authors called the safety profile unfavorable in that group. A 2026 review in the American Journal of Sports Medicine lists heart failure and insulin resistance as documented risks. The papers do not say why.
Other hormones. Cortisol rose in the 2008 trial, and total testosterone fell in a 1999 study of obese men.
Other groups. A 2018 dialysis study of 22 people reported no serious adverse effects attributable to MK-677. In a 2001 osteoporosis trial, few women left because of side effects.
Products sold online. A 2017 JAMA study found that 17 of 44 products sold as SARMs contained another drug, including ibutamoren. A 2025 European study of 324 seized samples found ibutamoren on top of the list, and said some samples were overdosed. A 2026 case report describes a ruptured spleen in a man who used MK-677 and another compound, and treats the link as speculative.
What is unknown. The 2018 review says long-term studies are few and that cancer and death rates with long-term use still need to be evaluated.

Frequently Asked Questions

What are the most commonly reported MK-677 side effects?

In the 2008 trial of healthy older adults, the most frequent were increased appetite, mild leg swelling, and muscle pain. Blood sugar and cortisol also rose.

Does MK-677 cause heart problems?

A hip fracture trial was stopped early over a congestive heart failure signal, and a 2026 review lists it among documented risks. The cause is not proven.

Is MK-677 safe long term?

That is not known. The longest controlled trial reviewed here lasted two years, and the 2018 review says long-term safety studies are needed.

Is MK-677 the same as ibutamoren?

Yes. Ibutamoren, MK-677, and MK-0677 are names for the same compound, and it has no approval as a medicine.

Key Takeaways

MK-677 is an oral, non-peptide compound that copies ghrelin and raises growth hormone, IGF-1, and cortisol.
It reliably raises growth hormone, but benefits for strength, recovery, and health are not shown.
Trials used fixed oral amounts in specific groups. No recommended amount exists.
Reported effects include appetite, leg swelling, higher blood sugar, and in one trial a heart failure signal.
Long-term safety is unknown, and products sold online vary in content.

Research Use Disclaimer

This content is provided for Research Use Only (RUO). The compounds discussed are not drugs, dietary supplements, foods, or cosmetics, and are not intended for human or animal consumption, diagnostic use, or therapeutic use of any kind. They have not been evaluated by the FDA for safety or efficacy in humans. Any research use must be conducted by qualified professionals in a controlled laboratory environment, in accordance with all applicable institutional, local, and federal regulations.

Sources

Wikipedia contributors. Ibutamoren. Wikipedia, The Free Encyclopedia.
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.
Bach MA, et al. The effects of MK-0677, an oral growth hormone secretagogue, in patients with hip fracture. J Am Geriatr Soc. 2004.
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.
Murphy MG, et al. Effect 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. J Clin Endocrinol Metab. 2001.
Murphy MG, et al. MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism. J Clin Endocrinol Metab. 1998.
Campbell GA, et al. Oral ghrelin receptor agonist MK-0677 increases serum insulin-like growth factor 1 in hemodialysis patients, a randomized blinded study. Nephrol Dial Transplant. 2018.
Chapman IM, et al. Stimulation 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. J Clin Endocrinol Metab. 1996.
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.
Svensson J, et al. Discrepancy between serum leptin values and total body fat in response to the oral growth hormone secretagogue MK-677. Clin Endocrinol. 1999.
Sevigny JJ, et al. Growth hormone secretagogue MK-677, no clinical effect on AD progression in a randomized trial. Neurology. 2008.
Fuh VL, Bach MA. Growth hormone secretagogues, mechanism of action and use in aging. Growth Horm IGF Res. 1998.
Sigalos JT, Pastuszak AW. The safety and efficacy of growth hormone secretagogues. Sex Med Rev. 2018.
Tewari K, et al. Peptide supplements and their therapeutic applications in sports medicine. Am J Sports Med. 2026.
Van Wagoner RM, et al. Chemical composition and labeling of substances marketed as selective androgen receptor modulators and sold via the internet. JAMA. 2017.
Barrios MM, et al. SARMs, metabolic modulators and growth hormone secretagogues in suspected illegal medicines, bought as sport performance enhancers. Drug Test Anal. 2025.
Jaffry K, et al. Spontaneous splenic rupture in a patient with recent use of performance-enhancing compounds, a case report and literature review. Cureus. 2026.

Explore the hormone therapy research category for related compounds, or view the Ipamorelin research material.