MK-677 (Ibutamoren)
Oral ghrelin mimetic. Bumps GH and IGF-1 without injections. Strong appetite stimulation is the trade-off.
MK-677 (Ibutamoren): Oral ghrelin mimetic. Bumps GH and IGF-1 without injections. Strong appetite stimulation is the trade-off. MK-677 is the only oral GH-axis compound that actually works.
MK-677 is the only oral GH-axis compound that actually works. It tricks your body into thinking it's hungry, which signals more GH release. Big appetite increase is the trade-off, great in a bulk, awful in a cut.
FDA places ibutamoren mesylate, the salt sold as MK-677, in Category 2 under both 503A and 503B. Its Category 2 compounding rationale specifically cites significant safety risks from the potential for congestive heart failure in certain patients, referring to a randomized placebo-controlled hip-fracture trial that was terminated early over that signal. That is the compounding rationale rather than the whole safety picture: FDA has separately warned about ibutamoren in consumer products over effects including raised appetite, water retention, fatigue, muscle pain and changes in glucose and insulin sensitivity, with long-term effects unknown. Category 2 also sits outside FDA's Category 1 interim policy, so FDA has said it would consider action under its general enforcement policies. It is not on the 503A bulks list.
Not prescribed in conventional medicine. Sometimes offered by anti-aging clinics off-label.
Wear a CGM the first 14 days.
Known glucose-elevating effect; monitor or skip. A two-week sensor (~$80, OTC, no prescription) tells you more about how YOUR body is responding to MK-677 (Ibutamoren) than any protocol guide can. Most users wear one and don't again. The first cycle is the one that matters.
Who it's for
- →Users who want GH benefits but won't inject
- →People in a bulking / mass-gain phase
- →Sleep-quality focused stacks
What to expect
- Week 1
Sharp appetite increase. Vivid dreams, deeper sleep.
- Week 4
Visible water retention, slight bloat. IGF-1 climbing.
- Week 8
Recovery and body comp shifts in users training hard.
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How it works (mechanism)
Oral non-peptide ghrelin-receptor agonist. Mimics ghrelin's signal to release GH and IGF-1. The same ghrelin signal also drives strong appetite stimulation, the trade-off of an oral GH-axis tool.
Dosing protocol
Stacks well with
Stack essentials
Side effects
When NOT to use
- ⚠Active malignancy
- ⚠Pre-diabetic or insulin-resistant baseline
- ⚠Pregnancy / nursing
Bloodwork to monitor
- • IGF-1 baseline + week 8
- • Fasting glucose / insulin every 8 weeks
Common mistakes
- • Running it during a cut (the appetite makes the cut nearly impossible)
- • Stacking with anything that raises insulin resistance further
- • Skipping cycle breaks
What it actually is
An orally active compound that mimics ghrelin, the hunger hormone, at its receptor. It is not a peptide and not growth hormone — it is a small molecule that makes your pituitary release more of your own growth hormone. It has never been approved for anything despite reaching late-stage trials, and it is banned in sport by WADA.
Ghrelin is released by an empty stomach and does two things: it makes you hungry and it triggers growth hormone release. MK-677 switches on the same receptor and produces both effects. Growth hormone and IGF-1 rise, and so does appetite, and the appetite is not a side effect you can separate out — it is the same signal. Because it acts on your own pituitary, the release keeps its natural pulsing pattern, which is the argument for it over injected growth hormone.
Forms, and which is which
Dosed once daily, usually at night. Orally active by design, which is its main practical advantage over injectable GH-axis compounds.
Verdict: The standard form.
Easier to take a fraction of a dose. Suspensions settle, so inconsistent shaking means inconsistent dosing.
Verdict: Flexible, and only as accurate as your shaking.
Cheapest per gram and requires an accurate milligram scale. Most kitchen scales cannot weigh 10-25 mg reliably.
Verdict: Cheap, and the dosing error is on you.
Sold as pre-mixed 'stacks'. Combines an unapproved compound with other unapproved compounds and makes any effect unattributable.
Verdict: Several unknowns in one capsule.
What it is claimed to do, graded
This is the best-established effect, shown repeatedly in randomised human trials going back to the 1990s. It measurably does what it says at the hormone level.
One randomised crossover trial in eight healthy men over seven days, measuring nitrogen balance rather than any clinical or functional outcome. Genuinely direct evidence, and about as small as a trial gets.
There is a compound-specific double-blind placebo-controlled crossover study: it reported increased stage IV and REM sleep, in eight young participants plus a separate six-person older group. Direct evidence, and very small, very old and very short.
A two-year randomised trial in healthy older adults found fat-free mass rose by 1.1 kg while falling 0.5 kg on placebo. Total and intracellular water both rose, and the authors read the intracellular change as consistent with an anabolic effect rather than simple fluid.
Fat-free mass on a scan is not the same as muscle hypertrophy, and the measured strength and functional outcomes in that trial did not improve. This is the reason most people take it, and it is the part that did not happen.
The adult programme did not deliver. A multicentre trial in people recovering from hip fracture missed most functional endpoints, gait speed improved on one measure, and the trial was stopped early over a congestive heart failure signal. Note that lack of approval is not the whole story: ibutamoren is separately in a recruiting phase 3 trial for paediatric growth hormone deficiency, a different indication entirely.
Grades describe how much human evidence exists for that specific claim, not whether it will work for you or whether it is safe.
Pros and cons
- • Oral, so no injections and no reconstitution
- • Raises IGF-1 measurably, and you can confirm that with bloodwork
- • Sleep improvement is the most consistently reported subjective effect
- • Preserves natural pulsatile growth hormone release rather than overriding it
- • Appetite increase is common and can be limiting; it is receptor-mediated and varies between people, and in the two-year trial it commonly subsided within a few months
- • Reduces insulin sensitivity and raises fasting glucose
- • A randomised hip-fracture trial was stopped early over a congestive heart failure signal, and FDA identifies potential heart failure as a significant safety risk for this compound
- • Water retention and carpal-tunnel-like numbness are common
- • Never approved — the late-stage trials failed to show functional benefit
- • Banned by WADA, so tested athletes are out
When to stop
- • New or worsening swelling WITH breathlessness, rapid weight gain, or any chest symptom — get assessed promptly rather than waiting it out. This is the heart failure signal, and it is the reason not to treat oedema on this compound as something that settles
- • Fasting glucose or A1C climbing out of range
- • Persistent numbness or tingling in the hands
- • Any new cancer diagnosis
- • You are entering a cut and cannot control intake
Interactions
Adds the insulin-resistance and fluid-retention risk of both with no established additional benefit.
It worsens insulin sensitivity, which works directly against those drugs.
Not a drug interaction, a practical one: the appetite stimulation makes maintaining a deficit substantially harder.
The most important line here. A randomised trial was terminated early over a congestive heart failure signal, and FDA lists potential heart failure among the significant safety risks for this substance.
Transient transaminase elevations have been reported. That is a reason for clinical evaluation, not a reason to assume a liver-support supplement makes it safe — no supplement has been shown to.
Is this for you?
- • People in a deliberate mass-gain phase who want GH-axis effects without injecting
- • Anyone who will actually run baseline and follow-up bloodwork
- • You are cutting — the appetite effect works directly against you
- • You are pre-diabetic or insulin resistant
- • You have active cancer
- • You have heart failure or are at high risk of fluid overload
- • You are drug-tested in sport
- • You are pregnant or nursing
The one number
Sources for the claims above
- Reverses diet-induced catabolism in healthy volunteers
- Safety and efficacy review of growth hormone secretagogues
- Two-year randomised trial of body composition and clinical outcomes in healthy older adults
- Hip-fracture trial stopped early over a congestive heart failure signal
- Controlled crossover study of sleep quality
Drug & supplement interactions
- ⚠Cortisol may bump slightly, caution if on glucocorticoid therapy
- ⚠Insulin sensitivity may decrease over time, diabetics monitor closely
- ⚠Strong appetite stimulation interferes with caloric-deficit goals
Community patterns
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Common questions about MK-677 (Ibutamoren)
Head-to-head with MK-677 (Ibutamoren)
Tracked alongside MK-677 (Ibutamoren)
Same goal, different aisle — each graded on its own evidence in the Pepdex catalog.
More in GH-axis
Recombinant human growth hormone, the protein itself, not a peptide that nudges your body to make more. Highest legal-risk compound in this catalog.
Bumps your natural growth-hormone pulses without hitting cortisol or prolactin. A selective GH secretagogue.
Pairs with Ipamorelin to amplify your natural growth-hormone pulses. A GHRH analog whose 'no-DAC' version stays short-acting on purpose.
Used to drive muscle growth. A long-acting form of insulin-like growth factor 1, with limited human safety data and a real side effect profile, handle with discipline.