Which is better, sermorelin or MK-677 (ibutamoren)?
MK-677 has the larger evidence base (including a 2 year, 65 person randomized trial showing about 1.1 kg more fat free mass than placebo), but that trial also showed higher fasting glucose and reduced insulin sensitivity with no strength or function benefit, and a phase 2b hip fracture trial was terminated for a possible congestive heart failure signal, which is the basis of FDA's Category 2 listing. Sermorelin has smaller and older human data but a former FDA approval, a Federal Register finding that it was not withdrawn for safety, and a lawful compounding path. Between an option with a legal channel and no heart failure signal and one with neither, sermorelin wins. [1] [4] [5] [9] [10]
How do sermorelin and MK-677 (ibutamoren) compare?
| Dimension | SermorelinFavored | MK-677 (ibutamoren) |
|---|---|---|
| Mechanism [1] [7] | GHRH receptor agonist (the 1-29 fragment of growth hormone releasing hormone). Stimulates pulsatile GH release from the pituitary, limited by somatostatin tone. | Non peptide ghrelin receptor (GHS-R1a) agonist. Amplifies GH pulse amplitude without changing pulse frequency and, as a ghrelin mimetic, increases hunger. |
| Note: Different receptors, same end point: more pituitary GH and higher IGF-1. | ||
| Human evidence [1] [2] [5] [6] [8] | Small and older: a 5 month single blind placebo controlled trial in 19 adults aged 55 to 71 raised nocturnal GH and IGF-1 and skin thickness, with lean mass and insulin sensitivity gains in men only. A 12 month open study in 18 short children raised height velocity from 4.8 to 7.2 cm per year. | Several randomized placebo controlled trials: 2 years in 65 older adults (about 1.1 kg more fat free mass, no strength or function benefit), 8 weeks in 24 obese men (about 3 kg more fat free mass, no fat loss), and 12 months in 563 people with Alzheimer disease (no clinical effect). |
| Key safety signal [1] [3] [5] [9] | Injection site reactions, flushing, and headache in the pediatric program; transient hyperlipidemia in the adult trial. No trial was stopped for safety. | A phase 2b hip fracture trial was terminated early for a possible congestive heart failure signal. The 2 year trial showed higher fasting glucose (about 0.3 mmol/L), reduced insulin sensitivity, edema, and muscle pain. |
| FDA and compounding status [4] [10] [11] | Formerly FDA approved as Geref (1990 diagnostic, 1997 pediatric GH deficiency); withdrawn by the sponsor, with a 2013 Federal Register finding that it was not withdrawn for safety or effectiveness. Not on the 503A Category 2 list; many 503A pharmacies compound it on a prescription. | Never FDA approved. Placed in 503B Category 2 in December 2022 and 503A Category 2 in September 2023 for the heart failure signal, and still listed as of April 2026, so licensed pharmacies cannot lawfully compound it. |
| Route and dosing frequency [1] [5] | Subcutaneous injection, usually nightly at bedtime; plasma half life of minutes. | Oral capsule or tablet once daily; long acting. |
| Doses used in the literature [1] [3] [5] [7] | Geref label: 30 ug/kg subcutaneously once daily at bedtime in children. Adult trial: 10 ug/kg nightly for 16 weeks. No established adult anti-aging dose. | 25 mg orally once daily in the main trials, with 2 mg and 50 mg arms in early studies. These are research doses, not an approved regimen. |
| Effect on appetite and glucose [1] [2] [5] | No appetite effect reported. Fasting glucose and insulin rose during pediatric treatment; insulin sensitivity improved in older men in the adult trial. | Increased appetite is the most common effect across trials, and glucose control worsens with long term use. |
| WADA status [12] | Prohibited at all times under S2 (GHRH and its analogues). | Prohibited at all times under S2 (ibutamoren is named as a GH secretagogue). |
| Note: Neither is permitted for tested athletes. | ||
| Typical cost and access [10] [11] | Compounded only, paid in cash through telehealth clinics that include the visit; there is no branded product. Dated prices are on the sermorelin cost page. | No lawful US channel. Products sold as research chemicals or supplements are not lawful for human use and are not verified for identity or purity. |
Evidence grade and regulatory status
Pulled from each peptide’s own record, so it stays in step with the peptide pages.
| Attribute | Sermorelin | MK-677 (ibutamoren) |
|---|---|---|
| Class | Synthetic 29 amino acid N-terminal fragment of human growth hormone releasing hormone (GHRH 1-29), the shortest fragment with full GHRH receptor activity | Oral non peptide growth hormone secretagogue (small molecule ghrelin receptor agonist) |
| What it is | Formerly FDA approved piece of growth hormone releasing hormone (Geref, withdrawn 2009 for business reasons); small trials show higher GH and IGF-1. | Oral ghrelin mimetic with real RCTs: raises IGF-1 and lean mass modestly, raises glucose and appetite, a heart failure signal stopped development. Not approved. |
| Evidence | Evidence: Human RCT evidence | Evidence: Human RCT evidence |
| FDA status | Regulatory: Regulatory status unknown | Regulatory: Not eligible for compounding |
| Compounding | There is no currently approved sermorelin product in the United States. Geref (sermorelin acetate) was approved as a diagnostic on December 28, 1990 (NDA 19-863) and for treatment of idiopathic growth hormone deficiency in children on September 26, 1997 (NDA 20-443); the sponsor discontinued both in 2008 and FDA withdrew the approvals effective June 18, 2009. In March 2013 FDA determined in the Federal Register that Geref was not withdrawn for reasons of safety or effectiveness, which allows generic applications. Sermorelin was not placed on the 503A Category 2 list in 2023 and is not on the 503A bulks list; many 503A pharmacies compound it on the basis of the former approval, and whether that satisfies the component of an approved drug condition depends on how a state board and the pharmacy read it. Compounded sermorelin for adult anti-aging, fat loss, or sleep is an unapproved use with no supporting trial. | Not FDA approved for any use. FDA placed ibutamoren mesylate in 503B Category 2 on December 29, 2022 and in 503A Category 2 on September 29, 2023, citing the potential for congestive heart failure based on the terminated hip fracture trial. As of the FDA page current to April 22, 2026, it remains in both categories, so no licensed pharmacy or outsourcing facility can lawfully compound it. It was not among the substances withdrawn from Category 2 in April 2026. It is widely sold online as a research chemical or mislabeled supplement. |
| WADA | WADA: WADA prohibited | WADA: WADA prohibited |
| Routes | Subcutaneous injection, usually at bedtime (approved and trial use), Intravenous bolus (former diagnostic use), Intranasal (research only, lower bioavailability), Oral tablets and troches sold by some compounders have no published pharmacokinetic data | Oral capsule or tablet, once daily (all trials and as sold) |
| Typical cost | About 105 to 180 USD per month for compounded sermorelin through licensed telehealth programs, including the consultation and medication. Research chemical listings are not lawful for human use. Prices checked 2026-09-22 on published provider and pharmacy price pages. | Not available through licensed US channels. Products sold as research chemicals are not lawful for human use and are not verified for identity or purity. |
| Last verified |
Has sermorelin been tested directly against MK-677 (ibutamoren)?
No published trial has compared sermorelin and MK-677 (ibutamoren) directly. The dimensions above come from separate studies and labels, and cross-trial comparisons are less reliable than a direct trial.
What do sermorelin and MK-677 (ibutamoren) cost?
| Dimension | Sermorelin | MK-677 (ibutamoren) |
|---|---|---|
| Typical cost | $105 to $180 per month | Not available through licensed US channels. Products sold as research chemicals are not lawful for human use and are not verified for identity or purity. |
| Price detail | Sermorelin price by channel | Price index in progress |
Where a price index exists, the range is the cash price per month across branded, compounded, and telehealth channels, without insurance. The cost pages give each channel separately with its sources. Otherwise the typical cost from the peptide record is shown. Legal access depends on your state: see peptide legality by state.
Frequently asked questions
Is MK-677 stronger than sermorelin?
No trial has compared them directly. MK-677 has larger and longer randomized trials showing sustained IGF-1 increases and about 1.1 kg more fat free mass than placebo over 2 years, but without strength or function gains. Sermorelin's human data are smaller and older. Stronger GH stimulation is not the same as better outcomes, and MK-677 carries a heart failure signal. [1] [5] [9]
Can a doctor prescribe MK-677?
Not through a lawful US pharmacy channel. FDA placed ibutamoren in both 503A and 503B Category 2, so compounding pharmacies and outsourcing facilities cannot lawfully make it, and it has never been approved. Sermorelin, by contrast, is compounded by 503A pharmacies on prescription. [10] [11]
Why is MK-677 on the FDA Category 2 list?
FDA cited the potential for congestive heart failure, based on a phase 2b trial in older adults recovering from hip fracture that was stopped early for that signal. Long term use also raised fasting glucose and reduced insulin sensitivity in a 2 year trial. [5] [9] [10]
Was sermorelin ever FDA approved?
Yes. Geref (sermorelin acetate) was approved as a diagnostic in 1990 and for idiopathic GH deficiency in children in 1997. The sponsor discontinued it and the approvals were withdrawn in 2009, and in 2013 FDA determined in the Federal Register that it was not withdrawn for reasons of safety or effectiveness. [3] [4]
Can athletes use either one?
No. Both are prohibited at all times on the WADA Prohibited List under S2: sermorelin as a GHRH analogue and ibutamoren as a named GH secretagogue. [12]
Conditions studied
From the blog
- Sermorelin vs HGH: mechanism, evidence, and legal status
Sermorelin signals the pituitary to release growth hormone; HGH (somatropin) is the hormone itself. Only somatropin is FDA approved today, and anti-aging use of either is off-label.
- Peptides for muscle growth, ranked by human evidence
MK-677, sermorelin, tesamorelin, CJC-1295, IGF-1 LR3, and more ranked by human evidence. None is approved for muscle growth, and all ten are banned in tested sport.
Sources
Numbered citations above point to these primary sources. PubMed entries link to the indexed abstract.
- [1]Khorram O, Laughlin GA, Yen SS. Endocrine and metabolic effects of long-term administration of [Nle27]growth hormone-releasing hormone-(1-29)-NH2 in age-advanced men and women. J Clin Endocrinol Metab 1997PubMed 9141536, 1997
- [2]Kirk JM et al. Treatment with GHRH(1-29)NH2 in children with idiopathic short stature induces a sustained increase in growth velocity. Clin Endocrinol (Oxf) 1994PubMed 7955460, 1994
- [3]Prakash A, Goa KL. Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency. BioDrugs 1999PubMed 18031173, 1999
- [4]Federal Register, March 4, 2013: Determination that Geref (sermorelin acetate) injection was not withdrawn from sale for reasons of safety or effectiveness (NDA 19-863 and NDA 20-443)Federal Register, 2013
- [5]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 2008PubMed 18981485, 2008
- [6]Svensson J et al. Two-month treatment of obese subjects with the oral GH secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure. J Clin Endocrinol Metab 1998PubMed 9467542, 1998
- [7]Chapman IM et al. Stimulation of the GH-IGF-I axis by daily oral administration of a GH secretogogue (MK-677) in healthy elderly subjects. J Clin Endocrinol Metab 1996PubMed 8954023, 1996
- [8]Sevigny JJ et al. Growth hormone secretagogue MK-677: no clinical effect on AD progression in a randomized trial. Neurology 2008PubMed 19015485, 2008
- [9]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 2011PubMed 21067829, 2011
- [10]FDA: Certain bulk drug substances for use in compounding may present significant safety risks (Category 2 list, content current as of April 22, 2026)FDA, 2026
- [11]FDA: Bulk drug substances used in compounding under section 503A of the FD&C Act (503A bulks list, Category 1, 2, and 3 lists)FDA, 2026
- [12]WADA Prohibited List, section S2 peptide hormones, growth factors, related substances and mimetics (GHRH analogues and GH secretagogues including ibutamoren)WADA, 2026
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