MK-677 Dosage: Oral Ranges & the Safety Picture
Last updated May 19, 2026 · Reviewed by Grey Peptides Editorial Board · ✓ Primary-sourced
← MK-677 encyclopedia entry · See also: Regulatory tracker · Peptides & muscle growth
MK-677 (ibutamoren) is not FDA approved for any use and has no label or prescribing information. Beyond the usual unknowns of an unregulated compound, MK-677 carries a specific concern: a clinical trial in older adults was stopped early over congestive-heart-failure signals, and the FDA cites that risk in its enforcement. It is also banned by WADA at all times. The doses below come from research and community use and are provided for education only — not as instructions for use.
The short version
MK-677 is a non-peptide small molecule that activates the ghrelin receptor (GHS-R1a), prompting the pituitary to release growth hormone in a roughly natural, pulsatile pattern and raising IGF-1. It is grouped with peptides by convention — clinics prescribe it alongside them — but chemically it is a conventional orally active drug. Because it is taken by mouth, there is no reconstitution and no injection: dosing is simply a daily oral amount. And because it is unapproved, there is no official dose, titration, or maximum.
Doses used in research
The published human studies give the most reliable anchor for what "a dose" means here, even though none support self-use:
| Study context | Daily oral dose | Reported effect |
|---|---|---|
| Healthy elderly, GH/IGF-1 axis | 10–25 mg | Dose-dependent rise in GH and IGF-1 |
| Obese adults, 8 weeks | 25 mg | Increased GH, fat-free mass; transient metabolic-rate bump |
| Older adults, 12 months | 25 mg | Fat-free mass up, but no strength/function gain; insulin sensitivity declined |
The 12-month trial is the most instructive: the lean-mass increase did not translate into measurable strength or functional improvement, while fasting glucose rose and insulin sensitivity worsened. In other words, the headline "muscle" effect was partly water and came with a metabolic cost.
What community use reports
Community use most commonly reports 10–25 mg once daily, often taken at night because some users find the appetite and drowsiness effects easier to manage during sleep, and because GH release is naturally concentrated in slow-wave sleep. These are descriptive observations, not a recommendation. Going above ~25 mg tends to amplify the side effects — hunger, fluid retention, and rising blood sugar — without a clear benefit.
Timing and half-life
MK-677 has a terminal half-life of roughly 4–8 hours, but its effect on IGF-1 is sustained across a full 24-hour interval, which is why once-daily dosing is typical regardless of the time chosen. The drug's oral bioavailability is high for an orally dosed molecule. You can explore how a once-daily oral compound behaves over a dosing cycle with our Half-Life Visualizer, and check potential conflicts with other medicines using the Interaction Checker — bearing in mind these are educational tools, not a substitute for clinical care.
Why dose discipline matters here
Three side effects are dose-related and worth understanding before reading any protocol. Appetite can be intense, especially in the first 4–6 weeks. Fluid retention and mild edema are common early and usually settle. Most importantly, fasting glucose and insulin resistance tend to rise, which is why people with diabetes or prediabetes are repeatedly flagged as poor candidates. Layered on top is the early-terminated heart-failure trial that anchors the FDA's safety position. None of this is managed by "starting low" alone — it reflects the pharmacology of sustained GH/IGF-1 elevation.
Where MK-677 stands legally
MK-677's regulatory path differs from injectable peptides like BPC-157 and TB-500. Merck developed it in the 1990s and discontinued the program in 1999. In October 2024 the PCAC reviewed ibutamoren mesylate for the 503A bulks list and recommended against inclusion, citing limited characterization, lack of effectiveness evidence, and specific safety concerns — so unlike BPC-157/TB-500, its compounding door is effectively closed rather than pending. The FDA has issued warning letters over products containing undeclared ibutamoren (including children's "growth" supplements in late 2025), and it is excluded from the dietary-supplement definition by statute. It is not a DEA-controlled substance, and is typically sold as a "research chemical." Meanwhile, LUM-201 — the same molecule under Lumos Pharma — is in Phase 2 trials for pediatric growth-hormone deficiency, the one active clinical development path. See the Regulatory Status Tracker for details.
Frequently asked questions
Morning or night?
Either works pharmacologically because the IGF-1 effect spans 24 hours. Night dosing is common anecdotally to align with natural GH pulses and to sleep through the appetite bump, but this is preference, not evidence.
Should the dose be "cycled"?
Community protocols often run blocks of weeks to months. There is no trial-based schedule, and the metabolic effects (glucose, insulin) are a reason some argue against continuous long-term use — but this remains unsettled without long-term human safety data.
Is the lean mass "real" muscle?
Partly water. The 12-month trial increased fat-free mass without improving strength or function, so the visible change overstates any performance benefit.
Sources
- Chapman IM, et al. "Stimulation of the GH–IGF-I axis by daily oral MK-677 in healthy elderly subjects." J Clin Endocrinol Metab. 1996;81:4249–4257.
- 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;149:601–611.
- U.S. FDA — PCAC briefing on ibutamoren mesylate (October 2024); warning letters on products containing undeclared ibutamoren (2024–2025).
Medical disclaimer: Education only, not medical advice. MK-677 (ibutamoren) is not approved for human use. Dosing figures reflect research and community reports, not a recommendation. Do not self-administer; consult a licensed clinician. The only verified-safe path to treatment is an FDA-approved medicine under a clinician's supervision.