Reviewed & approved by Dr. Nova Reyes · Last checked 2026-10-25. ← Back to Evidence Library
MK-677 (ibutamoren): what the evidence says
At a glance
What it is: ibutamoren (MK-677). It is not a peptide: it is an oral ghrelin-receptor agonist (a small-molecule pill) that makes the body release more growth hormone. R1, R3 It is included because it is sold alongside peptides.
What the evidence says: it reliably raises growth hormone and IGF-1 and added about 1 kg of lean mass in older adults over a year R1, but trials found no improvement in most function measures after hip fracture R2 and no effect on Alzheimer's disease. R3
Biggest risks: raised blood sugar and lowered insulin sensitivity R1, R4; a heart-failure safety signal stopped a hip-fracture trial early R2; increased appetite, swelling and muscle pain. R1
Rating
| Human Human evidence | Limited for raising GH/IGF-1 and lean mass R1, R4; Very limited (mixed results) for function or disease outcomes R2, R3; No human data for body-building use in young adults |
| Animal Animal / lab evidence | Reported (not reviewed for this page) |
| Regulatory | Not FDA-approved (no Drugs@FDA entry found) R6 · WADA: prohibited at all times, S2.2.4 R5 |
| Established human dose | None. Study details lists what trials used |
Evidence verdict: GH/IGF-1 and lean mass: Limited · Function or disease outcomes: Very limited (mixed results) · Gray-market body-building use: No human data Card verdict: Limited (raises GH/IGF-1 and lean mass) · Gray-market use: No human data Card note: Not a peptide: an oral ghrelin-receptor agonist. Varies by use, see page.
This page reports what studies used. It is not dosing advice.
Legend: HUMAN data · ANIMAL / LAB data · UNKNOWN · UNVERIFIED: not yet confirmed against a primary source
About the evidence: the trials below were run in the 1990s and 2000s, largely by or with the original developer (Merck) [UNVERIFIED: sponsor not stated in all abstracts].
What is it?
MK-677 is not a peptide. It is an oral ghrelin-receptor agonist, a small-molecule drug taken by mouth. It is included in this library because it is sold alongside peptides. It activates the ghrelin receptor, which raises growth hormone and IGF-1 levels. R1, R3 Gray-market sellers market it for muscle, sleep and recovery. Unknown Related pages: Ipamorelin, GHRP-6, Hexarelin.
Does it work?
- Human Healthy older adults (2 years): 65 adults aged 60–81: GH and IGF-1 rose to young-adult levels; lean mass +1.1 kg vs −0.5 kg on placebo; no change in belly fat. R1
- Human Obese men (8 weeks): 24 men: IGF-1 about +40%, lean mass increased; total and visceral fat unchanged. R4
- Human Hip fracture recovery: 123 older patients: gait speed improved slightly, most function measures did not; stopped early for a heart-failure signal. R2
- Human Alzheimer's disease: 563 randomized (416 completed), 12 months: IGF-1 up ~73%, no effect on disease progression. R3
- Unknown Muscle gain or recovery in young healthy adults: no trials found.
Is it safe?
- Human Blood sugar: fasting glucose up 0.3 mmol/L (5 mg/dL) and insulin sensitivity down R1; glucose tolerance impaired on testing. R4
- Human Heart failure signal: hip-fracture trial stopped early; authors call the safety profile "unfavorable" in that population. R2
- Human Common: increased appetite (faded over months), mild leg swelling, muscle pain. R1
- Unknown Long-term effects beyond 2 years unknown.
Gray-market "research use only" MK-677 (ibutamoren): extra risks
Unknown contents. Vials or capsules sold online as "research use only" are not made under drug-quality rules, so identity, strength and sterility are unknown. This is a general caution; we have not found independent testing data for this product. Unknown Vendor claims about effects in people are marketing, not evidence. Unknown
What we don't know
- Unknown Whether higher GH and IGF-1 bring real benefits, given the negative function and Alzheimer's trials
- Unknown Long-term cancer, heart or diabetes risk
- Unknown What is in gray-market capsules or liquids
Is it legal?
US: not FDA-approved; no application found in Drugs@FDA data under ibutamoren or MK-677 (Oct 25, 2026). R6 EU, UK and others: UNVERIFIED. WADA: ibutamoren (MK-677) is named among growth hormone secretagogues, S2.2.4, prohibited at all times. R5
Study details
These are amounts researchers used, not recommendations.
R1 Human RCT: healthy older adults (Nass 2008)
| Study | People / model | Route | Amount used | Follow-up | Reported | Side effects / limitations | Citation |
|---|---|---|---|---|---|---|---|
| Nass 2008 | 65 healthy adults aged 60–81 | Oral | 25 mg once daily | 2 years | GH/IGF-1 up; lean mass up; no change in visceral fat | Higher glucose, lower insulin sensitivity | PMID 18981485 |
R2 Human RCT: hip fracture (Adunsky 2011)
| Study | People / model | Route | Amount used | Follow-up | Reported | Side effects / limitations | Citation |
|---|---|---|---|---|---|---|---|
| Adunsky 2011 | 123 older hip-fracture patients | Oral | 25 mg/day | 24 weeks | IGF-1 up; gait speed up; most function measures unchanged | Stopped early for heart-failure signal | PMID 21067829 |
R3 Human RCT: Alzheimer's disease (Sevigny 2008)
| Study | People / model | Route | Amount used | Follow-up | Reported | Side effects / limitations | Citation |
|---|---|---|---|---|---|---|---|
| Sevigny 2008 | 563 randomized, 416 completed, mild-moderate AD | Oral | 25 mg daily | 12 months | IGF-1 up; no effect on progression | Negative trial | PMID 19015485 |
R4 Human RCT: obese men (Svensson 1998)
| Study | People / model | Route | Amount used | Follow-up | Reported | Side effects / limitations | Citation |
|---|---|---|---|---|---|---|---|
| Svensson 1998 | 24 obese men aged 18–50 | Oral | 25 mg daily | 8 weeks | IGF-1 ~+40%; lean mass up | Impaired glucose tolerance | PMID 9467542 |
Full reference list (PubMed entries checked Oct 25, 2026)
- R1 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. PMID 18981485
- R2 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. PMID 21067829
- R3 Sevigny JJ, et al. Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial. Neurology. 2008. PMID 19015485
- R4 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. PMID 9467542
- R5 WADA. The 2026 Prohibited List (in force 1 January 2026). https://www.wada-ama.org/en/prohibited-list
- R6 FDA. Drugs@FDA data (openFDA drugsfda endpoint), searched "ibutamoren" Oct 25, 2026: no application found. https://api.fda.gov/drug/drugsfda.json?search=products.active_ingredients.name:ibutamoren · Drugs@FDA: https://www.accessdata.fda.gov/scripts/cder/daf/ (a no-match search; Orange Book not separately checked)
Disclaimer
This page is for education and harm reduction, not medical advice or a recommendation to use MK-677 (ibutamoren). Talk to a clinician you trust before using any drug, and report problems to FDA MedWatch (https://www.fda.gov/safety/medwatch).
Approved for Adam Greene by Dr. Nova Reyes, 2026-10-25.