Is MK-677 FDA-approved, and what does the research show?

What is MK-677?

MK-677, or ibutamoren, mimics ghrelin, a hormone that stimulates growth hormone secretion ¹. The trials call it a growth hormone secretagogue, a substance that makes the body secrete its own growth hormone ².

Is MK-677 FDA-approved?

MK-677 is not FDA-approved ³. Drugs@FDA, FDA's record of approved drug products, holds no application for ibutamoren mesylate, the compound the trials call MK-677 ², ³. FDA's list of substances nominated for compounding under section 503A, updated May 14, 2026, places ibutamoren mesylate in Category 2 ⁴. FDA's heading for that category reads "Bulk Drug Substances that Raise Significant Safety Risks" ⁴.

See the FDA status of every peptide, updated weekly.

How does MK-677 work?

The trial authors propose that MK-677 activates the ghrelin receptor, the "likely mechanism" behind the growth hormone rise they measured ¹. Studied in people, 65 healthy men and women between 60 and 81 years old, MK-677 raised growth hormone and insulin-like growth factor I, or IGF-I, toward young-adult levels ¹. In a 12-month randomized trial of 563 patients with Alzheimer disease, MK-677 raised serum IGF-1 60.1% at six weeks and 72.9% at 12 months ².

What does the research show?

Studied in people: a two-year, double-blind, randomized trial of 65 healthy men and women between 60 and 81 years old, placebo-controlled for one year, crossed over in the second ¹. Fat-free mass and abdominal visceral fat at one year were the primary end points ¹. On MK-677 fat-free mass rose by 1.1 kg, while on placebo it fell by 0.5 kg ¹. Abdominal visceral fat and total fat mass did not differ between the groups ¹. The added fat-free mass "did not result in changes in strength or function," though the authors say the trial was too small and short to judge function ¹.

Studied in people: a double-blind, multicenter, randomized trial of 563 patients with mild to moderate Alzheimer disease, treated for 12 months ². MK-677 raised IGF-1 but did not differ from placebo on any of the four clinical scales used ². The authors concluded it "was ineffective at slowing the rate of progression of Alzheimer disease" ². The reference list for this page holds no human trial of MK-677 in younger adults, in athletes, or for sleep, as of November 9, 2026.

What are the side effects?

In the trial of 65 healthy older adults, the most frequent side effect was an increase in appetite that subsided within a few months ¹. Mild, transient swelling of the lower legs and muscle pain were also recorded ¹. Appetite rose in 67% of those on MK-677 against 36% on placebo ¹.

Fasting blood glucose rose by an average of 5 mg/dL and insulin sensitivity fell ¹. Cortisol rose, and bone density changed in a way the authors read as increased bone remodeling ¹. One woman left for raised fasting glucose and two for joint pain ¹. Two more left in the first year: a 68-year-old woman who had a heart attack seven days after starting MK-677, and an 82-year-old man diagnosed with a cancer of the tongue at 12 months ¹. The authors called MK-677 "generally well tolerated" over 12 months ¹. FDA's own words are its heading, "Bulk Drug Substances that Raise Significant Safety Risks"; the list gives no detail ⁴. FDA's own safety words on ibutamoren are on its page on the safety risks of nominated bulk substances, current as of April 22, 2026: ibutamoren mesylate "poses significant safety risks due to the potential for congestive heart failure in certain patients", citing a hip-fracture trial "terminated early due to a potential safety signal of congestive heart failure" ⁵.

In sport

WADA, the World Anti-Doping Agency, names ibutamoren (MK-677) on its 2026 Prohibited List under S2.2.4, "growth hormone releasing factors" ⁶. Class S2, peptide hormones, growth factors, related substances and mimetics, is prohibited at all times ⁶.

What JumpstartMD offers

JumpstartMD does not prescribe MK-677. Our peptide library covers it so you have the facts on its FDA status and the evidence, current as of November 9, 2026.

Ready to talk?

Book FREE Consultation

Share your details and a JumpstartMD team member will reach out shortly. Or call 408.478.3496 for your free, no-obligation consultation.

Share your details and a JumpstartMD team member will reach out when we open.

Disclaimer

Compounded medications are not FDA-approved, and FDA does not review their safety, effectiveness, or quality before they are marketed. A licensed clinician decides after an evaluation whether a peptide is appropriate for you, and not every patient will qualify.