Ipamorelin vs MK-677
An injectable selective peptide against an oral small molecule. MK-677 has by far the deeper trial record, and that record is largely what argues against it.
Short answer
With human clinical data on both sides, ipamorelin and MK-677 differ mainly in what they are for. Ipamorelin is marketed for muscle and fat loss; MK-677 is the choice for readers interested in muscle and sleep. Ipamorelin failed its primary endpoint in a randomized trial for bowel recovery after surgery; no muscle or fat-loss outcome trials.
Ipamorelin
Raises GH, but failed its one rigorous human efficacy RCT; no body-composition outcome data.
Full Ipamorelin evidence reviewMK-677
Ibutamoren
An oral ghrelin mimetic that reliably lifts GH, IGF-1 and lean mass — but the same trials found no gain in strength or function, plus metabolic and cardiac safety signals.
Full MK-677 evidence reviewIpamorelin vs MK-677: head to head
- FDA status / approved use
Ipamorelin
Not approved for its marketed uses; sold as unregulated research-use-only productsMK-677
Investigational; never approved or marketed; sold as a research chemical; prohibited in sport- Marketed for
Ipamorelin
Muscle, fat loss, 'anti-aging'MK-677
Muscle, sleep, 'anti-aging'- Outcome areas
Ipamorelin
Muscle / strength / lean mass; Weight loss / appetite; Longevity / lifespanMK-677
Muscle / strength / lean mass; Sleep; Longevity / lifespan- Evidence grade
Ipamorelin
Clinical dataMK-677
Clinical data- How it works
Ipamorelin
Selective ghrelin mimetic that triggers a growth hormone pulseMK-677
Oral ghrelin mimetic that amplifies the body's own growth hormone release- Route and dosing
Ipamorelin
Injection, usually sold together with CJC-1295MK-677
Oral, once daily; trials used 25 mg- Headline human result
Ipamorelin
Failed its primary endpoint in a randomized trial for bowel recovery after surgery; no muscle or fat-loss outcome trialsMK-677
Fat-free mass rose 1.1 kg vs a 0.5 kg loss on placebo, without strength or function gains, in a 2-year 2008 trial- Strongest evidence
Ipamorelin
Beck RCT, 2014Ipamorelin evidence reviewPubMed 25331030MK-677
Nass, Ann Intern Med 2008MK-677 evidence reviewPubMed 18981485- Key safety signal
Ipamorelin
Unverified dose, purity and identity; chronic GH/IGF-1 stimulation raises unaddressed safety concernsMK-677
Raises fasting blood sugar and lowers insulin sensitivity; a heart-failure signal stopped one trial- How it is obtained
Ipamorelin
Sold gray-market as a research chemical; no approved or legitimately compounded human productMK-677
Sold gray-market as a research chemical; no approved or legitimately compounded human product
| Ipamorelin | MK-677 | |
|---|---|---|
| FDA status / approved use | Not approved for its marketed uses; sold as unregulated research-use-only products | Investigational; never approved or marketed; sold as a research chemical; prohibited in sport |
| Marketed for | Muscle, fat loss, 'anti-aging' | Muscle, sleep, 'anti-aging' |
| Outcome areas | Muscle / strength / lean mass; Weight loss / appetite; Longevity / lifespan | Muscle / strength / lean mass; Sleep; Longevity / lifespan |
| Evidence grade | Clinical data | Clinical data |
| How it works | Selective ghrelin mimetic that triggers a growth hormone pulse | Oral ghrelin mimetic that amplifies the body's own growth hormone release |
| Route and dosing | Injection, usually sold together with CJC-1295 | Oral, once daily; trials used 25 mg |
| Headline human result | Failed its primary endpoint in a randomized trial for bowel recovery after surgery; no muscle or fat-loss outcome trials | Fat-free mass rose 1.1 kg vs a 0.5 kg loss on placebo, without strength or function gains, in a 2-year 2008 trial |
| Strongest evidence | Beck RCT, 2014Ipamorelin evidence reviewPubMed 25331030 | Nass, Ann Intern Med 2008MK-677 evidence reviewPubMed 18981485 |
| Key safety signal | Unverified dose, purity and identity; chronic GH/IGF-1 stimulation raises unaddressed safety concerns | Raises fasting blood sugar and lowers insulin sensitivity; a heart-failure signal stopped one trial |
| How it is obtained | Sold gray-market as a research chemical; no approved or legitimately compounded human product | Sold gray-market as a research chemical; no approved or legitimately compounded human product |
marks a row where the two differ. “Not established” marks a cell the available evidence does not answer. Evidence grades come from our evidence matrix, which grades each molecule on the human data for the use it is marketed for.
- Clinical data:
- Tested in humans — but investigational, discontinued, or proven only on a surrogate marker (not the marketed outcome).
Our verdict
MK-677 is not a peptide; it is an orally active ghrelin mimetic with the deepest human evidence base in this group. It reliably raises GH and IGF-1, and in a two-year randomized trial in healthy older adults it increased fat-free mass by 1.1 kg versus a 0.5 kg loss on placebo, yet the authors reported that gain did not result in changes in strength or function. It also raises fasting glucose, reduces insulin sensitivity, and a hip-fracture trial was terminated early for a heart-failure safety signal. Ipamorelin has a cleaner hormonal profile on paper but a much thinner record, and its one rigorous randomized human efficacy trial failed its primary endpoint. Neither is FDA-approved, both are sold as research chemicals, and they have not been compared directly.
Ipamorelin fits if
Ipamorelin is the one to read about if selectivity is your question, meaning a GH pulse with minimal cortisol, prolactin or appetite effect.
MK-677 fits if
MK-677 is the more instructive case if you want to see what happens when a GH secretagogue is actually taken to outcome trials; the biomarkers moved and the outcomes did not.
Ipamorelin vs MK-677: common questions
- Is either ipamorelin or MK-677 FDA-approved?
- No. Ipamorelin is not approved for its marketed uses; sold as unregulated research-use-only products. MK-677 is investigational; never approved or marketed; sold as a research chemical; prohibited in sport.
- Which has stronger human evidence, ipamorelin or MK-677?
- Neither clearly. Both have human clinical data. The key source for ipamorelin is Beck RCT, 2014; for MK-677, it is Nass, Ann Intern Med 2008.
- What are the main safety concerns with ipamorelin and MK-677?
- For ipamorelin, watch for unverified dose, purity and identity; chronic GH/IGF-1 stimulation raises unaddressed safety concerns. MK-677 raises fasting blood sugar and lowers insulin sensitivity; a heart-failure signal stopped one trial.
Key studies behind each
Ipamorelin
- Raun K, Hansen BS, Johansen NL, et al. (1998). Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. PubMed 9849822
- Teichman SL, Neale A, Lawrence B, et al. (2006). Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. J Clin Endocrinol Metab. PubMed 16352683
- Venkova K, Mann W, Nelson R, Greenwood-Van Meerveld B. (2009). Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus. J Pharmacol Exp Ther. PubMed 19289567
- Beck DE, Sweeney WB, McCarter MD; Ipamorelin 201 Study Group. (2014). Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. Int J Colorectal Dis. PubMed 25331030
MK-677
- Nass R, Pezzoli SS, Oliveri MC, et al. (2008). Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial. Ann Intern Med. PubMed 18981485
- Sevigny JJ, Ryan JM, van Dyck CH, et al. (2008). Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial. Neurology. PubMed 19015485
- Adunsky A, Chandler J, Heyden N, et al. (2011). MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study. Arch Gerontol Geriatr. PubMed 21067829
- Murphy MG, Plunkett LM, Gertz BJ, et al. (1998). MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism. J Clin Endocrinol Metab. PubMed 9467534
The full evidence reviews
- Ipamorelin & CJC-1295: the honest evidence on GH secretagogue peptides
They reliably raise growth hormone, and that part is real. The muscle, fat-loss and anti-aging claims are not supported by human outcome data. A straight read.
Updated October 2026
- MK-677 (ibutamoren): raises the hormones, not (yet) the outcomes
An oral ghrelin mimetic that reliably lifts GH, IGF-1 and lean mass in human trials — but the same trials found no gain in strength, function or cognition, plus real metabolic and cardiac safety signals.
Updated August 2026
Where to get it
Where to get peptide therapy
Clinician-led telehealth services that prescribe compounded peptides. The specific peptides offered vary by provider — confirm CJC-1295 & Ipamorelin availability before ordering.
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Compounded sermorelin within a broad longevity and weight-care menu
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