MK-677 (Ibutamoren) vs Tesamorelin
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
MK-677 (Ibutamoren)
MK-677, also known as Ibutamoren, is an orally active growth hormone secretagogue. Unlike peptides, it can be taken orally and has a long half-life, providing 24-hour GH elevation.
Full details →Tesamorelin
Tesamorelin is a synthetic analog of growth hormone-releasing hormone (GHRH). It is FDA-approved under the brand name Egrifta for reducing excess abdominal fat in HIV-infected patients with lipodystrophy.
Full details →Side-by-Side Comparison
| Aspect | MK-677 (Ibutamoren) | Tesamorelin |
|---|---|---|
| Dose Range | 10 mg–25 mg | 2 mg |
| Frequency | 1x daily | 1x daily |
| Cycle Length | 8–24 weeks | 8–52 weeks |
| Route | oral | subcutaneous |
| Mechanism | Acts as a potent, selective agonist of the ghrelin receptor (GHS-R1a). Increases GH and IGF-1 levels without affecting cortisol. Mimics ghrelin's GH-releasing effects. | Stimulates the pituitary gland to produce and release growth hormone by binding to GHRH receptors. Increases IGF-1 levels which promotes lipolysis and reduces visceral adipose tissue. |
| Typical Dosage | Typical dosing: 10-25mg taken orally once daily. Often taken at night due to sleep benefits and appetite increase. | FDA-approved dose: 2mg administered subcutaneously once daily. Research protocols may use various dosing schedules. |
| Administration | Oral administration (capsule or liquid). Can be taken with or without food. Long half-life allows once-daily dosing. | Subcutaneous injection into the abdomen. Rotate injection sites. Best administered at the same time daily, preferably in the evening. |
| Side Effects | Increased appetite and water retention are most common. May cause lethargy, vivid dreams, and mild numbness. Can affect blood glucose and insulin sensitivity. | Common side effects include injection site reactions (erythema, pruritus), joint pain, peripheral edema, and muscle pain. May cause elevated blood glucose. |
| Best For |
What They Have in Common
MK-677 (Ibutamoren), Tesamorelin are both commonly used for:
Key Differences
Unique to MK-677 (Ibutamoren):
Which Has Stronger Evidence?
- Muscle Growth: MK-677 (Ibutamoren) has stronger research support.
- Fat Loss: Tesamorelin has stronger research support.
| Goal | MK-677 (Ibutamoren) | Tesamorelin |
|---|---|---|
| Muscle Growth | high | medium |
| Fat Loss | medium | high |
Key Studies
MK-677 (Ibutamoren)
- Knowing the minimal detectable dose can facilitate the interpretation of a hair test result: II. Case example with ibutamoren (MK-677), a growth hormone secretagogue.
Clinica chimica acta; international journal of clinical chemistry, 2026
- Hepatotoxicity induced by MK-677.
BMJ case reports, 2025
- Investigating the P53-dependent anti-cancer effect of ibutamoren in human cancer cell lines.
Basic & clinical pharmacology & toxicology, 2025
Tesamorelin
- Tesamorelin as an Adjunct to Exercise for Improving Physical Function in HIV (TRIUMPH): a clinical trial protocol.
BMJ open, 2026
- Effects of Tesamorelin on Neurocognitive Impairment in Persons With HIV and Abdominal Obesity.
The Journal of infectious diseases, 2025
- Efficacy and safety of tesamorelin in people with HIV on integrase inhibitors.
AIDS (London, England), 2024
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