MK-677 (ibutamoren)
Not really a peptide: a pill-form chemical that raises growth hormone. It is not approved, and the FDA warns about heart failure risk.
Not an FDA-approved medicine. This alone does not tell you if it works.
Raised lean body mass in one trial, but not strength. Other trials did not help.
Hundreds of people. A trial stopped early for a heart failure warning sign.
These are 3 different questions. FDA status is about the law. Proof is about whether it works. Safety data is about how much we know about its risks. A lack of safety data does not mean it does not work, and "not approved" does not mean "illegal."
By the Peptide Science Desk Editorial TeamFact-checked against FDA and official sources · Not yet reviewed by a licensed clinician. How we check facts
What is it?
MK-677 is also called ibutamoren. It is NOT a peptide. It is a small lab-made chemical that you swallow. People group it with peptides because it acts like one: it tells your body to let out more growth hormone.
Why do people use it?
Some people use it hoping to build muscle, sleep better, or slow aging. These are claims. They are not proven facts.
Does it really work?
Studies in people show it raises growth hormone. In a 2008 study of healthy older adults, it added some lean body weight, but people did not get stronger or move better, and blood sugar went up. In a big 2008 study of people with Alzheimer’s, it did not slow the disease. A study in people healing from a broken hip was stopped early because of a possible heart failure warning sign.
Studies in people
| Study | People | What they found | Limits |
|---|---|---|---|
| Randomized trial | 65 older adults | Lean body mass up 1.1 kg, but no gain in strength or function. Blood sugar rose. | 2 years, but small. |
| Randomized trial | 563 with Alzheimer’s | Did not slow the disease. | 12 months. |
| Randomized trial (phase 2b) | 123 after hip fracture | Walking speed a bit better; most other tests no better. | Stopped early due to heart failure in some patients. |
Is it safe? Side effects
- The FDA says MK-677 poses significant safety risks because it may cause heart failure in some patients.
- In the study of older adults, blood sugar went up and the body handled sugar less well. Hunger went up, and some people had mild leg swelling and muscle pain.
- It is banned in sports at all times.
Is it legal in the US?
MK-677 (ibutamoren) is not an FDA-approved medicine.
- The FDA put it on its "Category 2" risky list for big "outsourcing" pharmacies on December 29, 2022, and for regular pharmacies on September 29, 2023.
- As of October 26, 2026, it is still on both lists. It is also banned in sports at all times.
What "not approved" does and does not mean
- "Not FDA approved" is not the same thing as "illegal." It means the FDA has not reviewed proof that it works and is safe.
- Outside the narrow pharmacy rules below, selling it as a medicine for people breaks federal law. The FDA has warned companies that sold unapproved drugs labeled "for research" or "not for human consumption" to people. (FDA)
- A regular pharmacy may only mix (compound) a drug from a raw ingredient that has an official quality standard, is part of an FDA-approved drug, or is on the FDA’s 503A list. Big "outsourcing" pharmacies (503B) have their own list. (FDA)
- The FDA says that in most cases it is illegal for people to bring unapproved drugs into the US for their own use. (FDA)
- State rules differ. State boards of pharmacy oversee most pharmacies day to day. Sports leagues and the military have their own bans. (FDA)
Banned in sports? Drug tests
Banned in sports.
Yes. WADA bans MK-677 (ibutamoren) at all times, in and out of competition. It is in section S2.2.4 of the 2026 list: growth hormone secretagogues, "ibutamoren (MK-677)".
Talk to your doctor
Do not start any peptide on your own. Ask a doctor first. We never share doses or tell you where to buy. Print our doctor questions sheet.
More questions
Is MK-677 a peptide or a SARM?
Neither. MK-677 (ibutamoren) is a small chemical taken by mouth. It acts like ghrelin to raise growth hormone.
Does MK-677 raise blood sugar?
Yes. In the 2-year study, fasting blood sugar went up about 5 mg/dL, and the body handled sugar less well.
Can MK-677 make you taller?
We found no study in people that tested MK-677 for height.
Related peptides
- IpamorelinNot approved · Proof: None found
- GHRP-6Not approved · Proof: Early
- CJC-1295Not approved · Proof: Early
Guides and tools
- Peptides vs TRT vs SARMs: which is safer?Guide
- Are Peptides Legal in the US?Guide
- Are Peptides Steroids? (Simple Answer)Guide
- FDA Category 2 Peptide List (2026): Which Peptides Are on It Now?Guide
- Do peptides really work? The honest answerGuide
- Can peptides cause blood clots, hair loss, diarrhea and more? Short answersGuide
- Drug test & sports ban checkerTool
- Compare MK-677 with another peptideTool
- Is my peptide source legit?Tool
- FDA warning letters trackerTool
Sources
- FDA: Bulk drug substances that may present significant safety risks
- FDA: Bulk drug substances nominated for 503A compounding (category lists, updated May 14, 2026)
- PubMed: Adunsky et al., MK-0677 (ibutamoren) after hip fracture, trial stopped early, Arch Gerontol Geriatr 2011
- PubMed: Nass et al., MK-677 in healthy older adults, Ann Intern Med 2008
- PubMed: Sevigny et al., MK-677 had no effect on Alzheimer’s disease, Neurology 2008
- WADA: 2026 Prohibited List (sports anti-doping rules)