MK-677
Also called ibutamoren, ibutamoren mesylate, MK-0677, L-163,191 and LUM-2011, 15
MK-677 is not a peptide. It is a small molecule taken by mouth that acts like ghrelin, the hunger hormone, and makes the body release more growth hormone.4, 15 It has been tested in randomized trials in older adults, in hip fracture recovery and in Alzheimer's disease. It raised growth hormone and lean mass, but strength and function didn't improve in older adults. A hip fracture trial found faster walking but no gain in most other measures, and was stopped early for heart failure, Blood sugar rose in several trials.3, 4, 5 It is not approved, can't be compounded and is not a legal supplement.1, 10
Often discussed alongside growth hormone peptides such as ipamorelin. See the peptide regulatory tracker for how they compare legally.
In this guide
At a glance
| What it is | An oral small-molecule ghrelin-receptor agonist (growth hormone secretagogue). Not a peptide4, 15 |
|---|---|
| Taken | By mouth, once a day, in every human trial3, 4 |
| Best evidence | A randomized trial in 65 healthy adults aged 60 to 81: growth hormone and IGF-1 rose to young-adult levels and lean mass rose 1.1 kg at 12 months. The trial ran up to 2 years4 |
| What it didn't do | Improve strength or function in older adults. Slow Alzheimer's disease. Improve most measures after hip fracture3, 4, 5 |
| No human evidence for | Muscle or strength in young, healthy people or athletes. Fat loss. Anti-aging |
| Main risks | Heart failure signal, higher blood sugar and lower insulin sensitivity, water retention, more appetite1, 3, 4, 9 |
| Legal status | Not FDA-approved. Can't be compounded. Not a lawful supplement ingredient1, 2, 10 |
| In sport | Banned at all times (WADA S2.2.4). No therapeutic exemption is granted12, 13 |
| Typical cost | No legal source to price |
Where to get it
MoveWell sells nothing and earns nothing from this page. There is no legal way to buy MK-677 in the US. Why
Not approved, and FDA bars pharmacies from compounding it. The 2026 HHS peptide policy doesn't cover it.1, 17
WhyFor children aged 3 to 11 with growth hormone deficiency. Not open to adults.14
See the trialMolecular structure
A small molecule, not a chain of amino acids. A spiropiperidine ring system carries a methanesulfonyl group and is joined by amide bonds to two modified amino-acid units.
The spiropiperidine ring system, the non-peptide core
- Type
- Small molecule, taken by mouth
- Formula
- C27H36N4O5S
- Weight
- 528.7 g/mol
- Salt studied
- Ibutamoren mesylate
- PubChem
- CID 178024
- Target
- Ghrelin receptor (growth hormone secretagogue receptor)
Drawn from the PubChem structure. Formula and weight are for the free base.16 FDA lists the mesylate salt.1
What it is
MK-677 was developed by Merck in the 1990s as a pill that raises growth hormone. Researchers describe it as an "oral ghrelin mimetic": it switches on the same receptor as ghrelin, the hormone that drives hunger and growth hormone release.4
It is often sold as a "peptide" or grouped with SARMs, but it is neither. Lumos Pharma, which now develops it as LUM-201, calls it "an orally administered small molecule."15 That's why it works as a pill, when most peptides have to be injected.
How it works
- Ghrelin receptor. It binds the ghrelin receptor in the brain and pituitary, which triggers pulses of growth hormone.4
- IGF-1. More growth hormone raises IGF-1 from the liver. In trials IGF-1 rose by about 40% to 80%.7, 8
- Appetite. Because it mimics the hunger hormone, appetite rises, at least for the first few months.4
- Blood sugar. Growth hormone works against insulin. Fasting glucose rose and insulin sensitivity fell in trials.4, 8
Unlike most compounds on this site, these effects were measured in people in randomized trials.
Evidence map
Each claimed use is graded separately. A grade measures how much evidence exists, not whether the result was good news.
Consistent in several small and mid-size randomized trials. A lab number, not a health outcome
One trial of 65 people: +1.1 kg lean mass at 12 months, but no gain in strength or function. Too small to test function well
One trial of 123 people: faster walking and fewer falls, most other measures unchanged. Stopped early for heart failure
One 12-month randomized trial. No effect on the disease
Small short studies raised IGF-1. A phase 3 trial in children is under way
No study found. User reports only
Scale: 5 FDA-approved, 4 strong human, 3 limited human, 2 animal or lab only, 1 anecdotal
Key studies
| Use | Study | Model | Finding |
|---|---|---|---|
| Aging | Nass 20084 | Human RCT n=65, aged 60–81 | 25 mg daily, 1-year primary results, 2-year follow-up. Lean mass +1.1 kg vs −0.5 kg on placebo. Weight +2.7 kg vs +0.8 kg. No change in strength or function, though the authors say the trial was underpowered for these. Fasting glucose up 5 mg/dL |
| Hip fracture | Adunsky 20113 | Human RCT n=123 | 25 mg daily. Faster walking and fewer falls; stair climbing and most other measures not significant. Stopped early for a heart failure signal |
| Alzheimer's | Sevigny 20085, 6 | Human RCT 12 months | IGF-1 rose, but the disease progressed the same as on placebo |
| Obesity | Svensson 19988 | Human RCT n=24 men | 25 mg daily for 8 weeks. Lean mass up, fat mass unchanged. Glucose tolerance got worse |
| GH deficiency | Chapman 19977 | Human crossover n=9 men | 4 days per dose. IGF-1 up 52% to 79%. Insulin and after-meal glucose rose |
| GH deficiency | NCT0694821414 | Recruiting planned n=150 children | Phase 3, LUM-201 vs placebo in children aged 3 to 11. Estimated completion Jan 2028 |
These trials were in older adults, patients and obese men, not in young athletes. No published trial tested MK-677 for bodybuilding.
By goal
Pick your goal to see what the evidence supports.
| Goal | Human evidence | Result |
|---|---|---|
| Muscle in young adults | None found | Unknown |
| Lean mass in older adults | One RCT, n=65, 1 to 2 years | +1.1 kg lean mass, no strength gain |
| Fat loss | One 8-week RCT in obese men, n=24 | Fat mass unchanged |
| Memory or Alzheimer's | One 12-month RCT | No effect |
| Recovery after hip fracture | One RCT, n=123 | Mixed. Stopped for heart failure |
Sources: Nass 2008,4 Svensson 1998,8 Sevigny 2008,5 Adunsky 2011.3
How it's used
No dose is approved for any use. In trials it was a pill taken once a day, in older adults or patients under medical supervision.3, 4 Those trials tracked blood sugar, heart failure and other side effects; buying it online skips all of that. We don't give a dose.
Side effects and who should avoid it
- Heart failure. The hip fracture trial "was terminated early due to a safety signal of congestive heart failure."3 FDA says ibutamoren "poses significant safety risks due to the potential for congestive heart failure in certain patients."1
- Blood sugar and insulin resistance. Over 1 to 2 years in older adults, fasting glucose rose and insulin sensitivity fell.4 Glucose tolerance worsened in obese men within 2 weeks.8 People with diabetes or prediabetes have the most to lose.
- Water retention. Mild, short-lived swelling of the legs was among the most common side effects in the older-adult trial, with more appetite and muscle pain. FDA also lists water retention.4, 9
- Appetite. Appetite rose and then eased within a few months. Weight went up 2.7 kg, versus 0.8 kg on placebo.4
- Other. Muscle pain, fatigue and a rise in cortisol.4, 9 FDA says "long-term effects of ibutamoren use are unknown."9
- Hidden in products. In 2025 FDA found unlisted ibutamoren in a growth formula sold for children aged five and older.9
- With SARMs. FDA warns ibutamoren may interact with SARMs in "potentially harmful" ways.9
- Athletes and service members. Banned by WADA at all times, and on the Defense Department's prohibited supplement ingredient list.11, 12
- Pregnancy, breastfeeding and children. No safety data outside the pediatric trial.
Compared with
| MK-677 | Ipamorelin | |
|---|---|---|
| What it is | Small molecule, by mouth | Peptide |
| Target | Ghrelin receptor | Ghrelin receptor |
| FDA advisory vote, Oct 2024 | 1–13 against | 0–12–1 against |
| HHS policy, Oct 2026 | Not covered | Not covered |
| In sport | Banned, WADA S2.2.4 | Banned, WADA S2.2.4 |
Sources: FDA advisory committee minutes,2 HHS Appendix B,17 WADA 2026 list.12 We don't have an ipamorelin guide yet.
Stacks
No combination with MK-677 has been tested in people.
MK-677 + SARMs
No dataCommon in bodybuilding. FDA warns the combination may be "potentially harmful." Neither is legal to sell as a supplement.9, 10
MK-677 + ipamorelin or CJC-1295
No dataAll push growth hormone. No study of the combination. FDA's advisers voted against compounding each one.2
Myths vs evidence
All options
MoveWell sells nothing and has no commercial link on this page. Checked November 1, 2026
| Route | Status | Why |
|---|---|---|
| Prescription drug | None | Not FDA-approved for any use1 |
| Compounding pharmacy | Not allowed | On FDA's Category 2 list since 2023. Advisers voted 1–13 against. Not in the HHS policy1, 2, 17 |
| Telehealth | None found | Superpower, which offers compounded peptides, doesn't list it19 |
| Supplement | Not lawful | FDA warning letter, Dec 202510 |
| Clinical trial | Children only | LUM-201 phase 3, ages 3 to 11 with growth hormone deficiency14 |
Research use only vials
We don't list sellers. "Research use only" MK-677 is sold outside FDA's drug and supplement rules, and FDA says ibutamoren can't be sold as a supplement.10 In August 2026 FDA warned five peptide sellers that the label doesn't excuse products clearly meant for people.18
Legal status history
Newest first.
- Current statusNot FDA-approved. In Category 2, so pharmacies can't compound it. Not covered by the HHS peptide policy. Not a lawful supplement. Banned in sport.1, 10, 12, 17
- Results of the LUM-201 phase 3 trial in children with growth hormone deficiency.14
- HHS enforcement discretion policy covers six peptides. MK-677 is not one of them.17
- Phase 3 trial of LUM-201 (ibutamoren) in children starts.14
- FDA warning letter: a "GE Labs MK 677" supplement is an unapproved new drug, and ibutamoren can't be a dietary supplement.10
- FDA warns consumers about a children's growth formula with hidden ibutamoren.9
- FDA's compounding advisory committee votes 1–13 against adding ibutamoren mesylate to the compounding list.2
- Defense Department's Operation Supplement Safety notes that MK-677 is on its Prohibited Dietary Supplement Ingredients list.11
- Placed in Category 2 for 503A pharmacies, citing heart failure risk. It had been in Category 2 for 503B outsourcing facilities since Dec 29, 2022.1
- Hip fracture trial published. It was stopped early for a heart failure signal.3
FAQ
Is MK-677 a peptide?
No. It's a small molecule taken by mouth that acts on the ghrelin receptor. It's sold alongside peptides, which is why it's in our library.
Is MK-677 legal?
It isn't FDA-approved, pharmacies can't compound it, and FDA says it isn't a lawful supplement ingredient. The only legal use in people is in a registered clinical trial.
Did the 2026 HHS peptide policy change anything?
No. The policy covers six peptides: BPC-157, TB-500, epitalon, semax, KPV and MOTS-c. MK-677 isn't one of them.
Does it build muscle?
In older adults it added about 1 kg of lean mass over a year, but strength and function didn't improve. No trial tested it in young, healthy people.
Is it safe?
It's been tested in people, but the trials raised safety concerns. A hip fracture trial was stopped early for heart failure, and blood sugar rose and insulin sensitivity fell in several trials.
What dose do people use?
No dose is approved for any use. We don't give one.
Can athletes use it?
No. WADA lists it under S2.2.4, banned in and out of competition, and Sport Integrity Australia says no therapeutic exemption would be granted.
Is it being developed as a drug?
Yes. Lumos Pharma is testing it as LUM-201 in a phase 3 trial in children with growth hormone deficiency.
References
19 sources, with links
- FDA. Certain bulk drug substances for use in compounding that may present significant safety risks (Category 2: ibutamoren mesylate; current as of Apr 22, 2026). fda.gov
- FDA. Final summary minutes of the Pharmacy Compounding Advisory Committee meeting, Oct 29, 2024. fda.gov
- 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(2):183–189. DOI 10.1016/j.archger.2010.10.004
- Nass R, Pezzoli SS, Oliveri MC, 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(9):601–611. DOI 10.7326/0003-4819-149-9-200811040-00003
- Sevigny JJ, Ryan JM, van Dyck CH, et al. Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial. Neurology 2008;71(21):1702–1708. PubMed
- ClinicalTrials.gov. NCT00074529: Study of MK0677 for the treatment of Alzheimer's disease (0677-030). clinicaltrials.gov
- Chapman IM et al. Oral administration of growth hormone (GH) releasing peptide-mimetic MK-677 stimulates the GH/insulin-like growth factor-I axis in selected GH-deficient adults. J Clin Endocrinol Metab 1997. PubMed
- 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. PubMed
- FDA. Agebox iKids Growth Day Formula may be harmful due to hidden ingredient (Sep 23, 2025). fda.gov
- FDA. Warning letter 719339 to Musclepower Enterprise Ltd dba Monster King and GE Labs (Dec 12, 2025). fda.gov
- Operation Supplement Safety (US Department of Defense). Performance-enhancing substance: MK-677 (ibutamoren) (Feb 23, 2024). opss.org
- World Anti-Doping Agency. 2026 Prohibited List, S2.2.4 growth hormone secretagogues. PDF
- Sport Integrity Australia. Ibutamoren (MK-677). sportintegrity.gov.au
- ClinicalTrials.gov. NCT06948214: Phase 3 study of LUM-201 in children with growth hormone deficiency (updated Oct 16, 2026). clinicaltrials.gov
- Lumos Pharma. Corporate document (Mar 20, 2024): "LUM-201 (ibutamoren) is an orally administered small molecule." PDF
- PubChem CID 178024, ibutamoren (via PubChemLite). Link
- HHS. 503A peptide enforcement discretion policy, Appendix B (Oct 28, 2026). hhs.gov; Federal Register public inspection, FR Doc. 2026-22192. Link
- ArentFox Schiff. RUO-ined: five peptide vendors learn research use only is not a legal strategy (Sep 18, 2026; on FDA warning letters of Aug 24, 2026). Link
- Superpower. Peptides page (checked Nov 1, 2026; MK-677 not listed). Link
What changed on this page. The earlier version called MK-677 a "research peptide," listed a dose range and said it seemed to have "a relatively safe side effect profile." It isn't a peptide, MoveWell gives no doses, and FDA flags a heart failure risk.1, 15
This page is for education and is not medical advice. MK-677 is not FDA-approved. Talk to a clinician before taking anything that changes your hormones.