MK-677 vs HGH
MK-677 (ibutamoren) is a pill that makes the pituitary release more of its own growth hormone. HGH (somatropin) is growth hormone itself, given by injection. Only HGH is an approved drug, and neither made healthy adults stronger in trials.
- MK-677
- Human studiesOnce daily
- Somatropin (HGH)
- Approved drugOnce daily
- Head-to-head trials
- None published
The short answer
MK-677 is a small molecule, not a peptide. It acts like the hunger hormone ghrelin on the pituitary, so the body releases more of its own growth hormone, and one daily pill keeps GH and IGF-1 raised. Somatropin is the 191-amino-acid growth hormone protein itself, made in cells and injected under the skin once a day.
Somatropin has been FDA-approved since 1987 for growth hormone deficiency and for HIV-associated wasting, and distributing it for other uses is a federal crime. MK-677 is approved nowhere: a hip-fracture trial was stopped early over heart failure, and FDA has placed it in Category 2 for compounding. In healthy adults both raised lean mass without making people stronger: about 1 kg over a year of MK-677 in older adults, and 2.1 kg, much of it water, in trials of growth hormone in fit young adults.
At a glance
| Field | MK-677Ibutamoren mesylate, MK-0677, L-163,191, LUM-201 | Somatropin (HGH)Human growth hormone, rhGH; Genotropin, Humatrope, Norditropin, Omnitrope, Saizen, Zomacton, Serostim, Nutropin AQ |
|---|---|---|
| Evidence | Human studies | Approved drug |
| Class | Ghrelin-receptor agonist (oral GH secretagogue) | Recombinant human growth hormone |
| Approval | Not approved as a drug in the US, EU or anywhere else. As LUM-201 it is in a Phase 3 trial in children with growth hormone deficiency (started May 2026); the EU gave it orphan designation for that condition in 2017. | Approved in the US since 1987 as Genotropin, Humatrope, Norditropin, Omnitrope and Zomacton for adults with growth hormone deficiency and several growth disorders in children, and as Serostim for HIV-associated wasting; Zorbtive, approved for short bowel syndrome, has no current listing. Distributing it for any other use is a federal crime, with up to 5 years in prison. |
| Sport (WADA 2026) | Banned in sport | Banned in sport |
| Common dose | 10–25 mg daily by mouth | 0.2–1 mg (0.6–3 IU) daily (label); 2–4 IU (community) |
| Frequency | Once daily | Once daily |
| Cycle | No set cycle | Continuous |
| Route | By mouth | Subcutaneous injection |
| Half-life | – | about 2–4 hours Label |
| Typical draw | – | 20 units10 IU with 1 mL, 2 IU |
| Vial sizes or form | By mouth | 10, 24, 36 IU |
| Human studies | 5 listedLargest: 563 people (2008) | 5 listedLargest: 3,400 people (2012) |
| Main cautions |
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| Open MK-677 | Open Somatropin (HGH) |
Doses shown are what labels, trials or community reports reference, not recommendations. Each compound’s page has the full detail and sources.
Key differences
What it is
MK-677: ibutamoren mesylate, a small molecule that mimics ghrelin at the pituitary. HGH: recombinant somatropin, the same 191-amino-acid protein the pituitary makes.
How it’s taken
MK-677: a pill once a day, often at bedtime. HGH: an injection under the skin once a day; the weekly long-acting versions are different molecules.
Approval
LabelHGH: FDA-approved since 1987 for growth hormone deficiency in adults and children and for HIV-associated wasting. MK-677: not approved anywhere; FDA lists it in Category 2 for compounding over the risk of heart failure.
Human evidence
TrialHGH: 54 placebo-controlled trials in adults with growth hormone deficiency (body fat down 2.56 kg, lean mass up 1.38 kg vs placebo). MK-677: trials in older adults; a year of 25 mg a day added 1.1 kg of lean mass with no change in strength or function, and a 563-person Alzheimer’s trial found no benefit.
Doses
HGH: adults with growth hormone deficiency start at about 0.2 mg a day (roughly 0.6 IU), adjusted by IGF-1 (label); research-vial use is often 2–4 IU a day (community). MK-677: 25 mg once a day in most adult trials.
Side effects
Both raise blood sugar by lowering insulin sensitivity. MK-677 also raises appetite and causes water retention and muscle or joint pain; HGH causes swelling, joint and muscle pain, tingling and carpal tunnel syndrome, mostly early and at higher doses.
Safety signals
MK-677: heart failure ended a hip-fracture trial early (4 of 62 people vs 1 of 61 on placebo). HGH: ruled out with active cancer and in acute critical illness, where two intensive-care trials found more deaths on it.
Sport
LabelBoth are banned at all times: HGH under WADA’s S2.2.3 (growth hormone) and MK-677 under S2.2.4 (growth hormone releasing factors).
Head-to-head studies
Taking them together
MK-677 and somatropin (HGH) each raise growth hormone or IGF-1 activity. Tesamorelin’s label advises monitoring IGF-1 and lists fluid retention, joint pain and higher blood sugar as side effects.
Source: Egrifta prescribing information
Open them in the stack check for sport status and one combined tracking checklist.
Questions
What is the difference between MK-677 and somatropin (HGH)?
MK-677 is a small molecule, not a peptide. It acts like the hunger hormone ghrelin on the pituitary, so the body releases more of its own growth hormone, and one daily pill keeps GH and IGF-1 raised. Somatropin is the 191-amino-acid growth hormone protein itself, made in cells and injected under the skin once a day.
Is MK-677 as good as HGH?
No trial in adults has compared them. MK-677 raises the body’s own GH and IGF-1, while HGH supplies the hormone. In healthy adults neither made people stronger: MK-677 added about 1 kg of lean mass over a year in older adults, and HGH about 2.1 kg, much of it water, in fit young adults.
Can MK-677 replace HGH for growth hormone deficiency?
Not on current evidence. MK-677 isn’t approved for anything. Somatropin is the approved treatment for adults with growth hormone deficiency, started low and adjusted by IGF-1 levels under a specialist.
Which affects blood sugar more?
Both raise it, and they haven’t been compared. In MK-677’s Alzheimer’s trial, blood sugar rose in 15.4% of people vs 4.6% on placebo. HGH labels warn of lower insulin sensitivity and report new type 2 diabetes.
Can MK-677 and somatropin (HGH) be taken together?
The stack check flags several growth hormone compounds. MK-677 and somatropin (HGH) each raise growth hormone or IGF-1 activity. Tesamorelin’s label advises monitoring IGF-1 and lists fluid retention, joint pain and higher blood sugar as side effects. No published study has tested them together.
Which has more evidence in people, MK-677 or somatropin (HGH)?
MK-677 is in clinical trials and not approved; its page lists 5 key human studies. Somatropin (HGH) is approved in the US; its page lists 5 key human studies. They haven’t been compared directly in a published trial.
Are MK-677 and somatropin (HGH) banned in sport?
MK-677 and somatropin (HGH) are banned at all times. This follows the WADA 2026 Prohibited List; athletes should confirm with their anti-doping organization.
Sources
- Genotropin, Humatrope, Norditropin, Omnitrope, Zomacton and Serostim prescribing information (DailyMed, 2025–2026)
- FDA, bulk drug substances that raise significant safety concerns (April 2026)
- Nass et al., MK-677 for 2 years in healthy older adults (Ann Intern Med 2008) PMID 18981485
- Adunsky et al., MK-677 after hip fracture (Arch Gerontol Geriatr 2011) PMID 21067829
- Sevigny et al., MK-677 in Alzheimer’s disease (Neurology 2008) PMID 19015485
- Hazem et al., GH therapy in adults with GH deficiency, meta-analysis (Eur J Endocrinol 2012) PMID 21865409
- Liu et al., growth hormone and athletic performance, systematic review (Ann Intern Med 2008) PMID 18347346
- WADA 2026 Prohibited List, sections S2.2.3 and S2.2.4
Each compound’s page lists its full sources: MK-677, Somatropin (HGH).