MK-677 (Ibutamoren) is a compound that has garnered significant attention, particularly within the fitness community. It functions as a growth hormone secretagogue, stimulating the body’s production and release of growth hormone (GH) and insulin-like growth factor 1 (IGF-1). Concerns about its potential impact on liver health are frequently raised, leading many to question the scientific evidence on MK-677’s liver toxicity. This article explores what current research indicates regarding this compound and its effects on the liver.
Understanding MK-677
MK-677 (Ibutamoren Mesylate) is an orally active, non-peptide compound. It is classified as a growth hormone secretagogue because it mimics ghrelin, a natural hormone, by binding to the ghrelin receptor (GHS-R1a) in the brain’s hypothalamus and pituitary gland. This interaction prompts the pituitary gland to release pulses of growth hormone, thereby elevating both GH and IGF-1 levels in the body.
The compound was initially developed for research purposes to address conditions such as growth hormone deficiency and muscle wasting. Its mechanism, stimulating natural processes rather than introducing exogenous hormones, distinguishes it from anabolic steroids or direct human growth hormone injections. MK-677’s ability to increase GH and IGF-1 levels has led to its investigation for various potential therapeutic applications, including improving muscle mass and bone mineral density.
Liver Toxicity: The Current Evidence
Scientific investigations into MK-677’s impact on liver health suggest a low risk of direct liver toxicity in healthy individuals at studied dosages. Unlike some other performance-enhancing compounds that can bind to androgen receptors and directly strain the liver, MK-677 operates through a different mechanism by stimulating ghrelin receptors. This indirect action on growth hormone release bypasses many of the pathways commonly associated with liver damage from more aggressive substances.
Clinical studies on MK-677 have reported minimal or no significant changes in liver enzymes, indicators of liver health. For instance, research involving healthy young men treated with MK-677 showed it was well-tolerated without significant adverse effects on liver function. While some users might experience minor, temporary fluctuations in liver enzyme levels, these return to normal once the compound is discontinued.
Despite low direct hepatotoxicity, a recent case report in 2025 described an otherwise healthy man who developed transaminitis after two months of MK-677 use. His liver function tests returned to normal after he stopped the supplement, suggesting a potential link in this specific instance. It is also important to consider that unverified products, often sold as research chemicals, may contain contaminants or undisclosed ingredients that could pose a risk to liver health. When MK-677 is used in conjunction with other substances, such as Selective Androgen Receptor Modulators (SARMs), there is a greater potential for negative impacts on liver enzymes, as SARMs themselves are known to be associated with liver damage.
Responsible Use and Monitoring
Given that MK-677 is not approved for human consumption by regulatory bodies like the FDA, its use is considered experimental. Individuals considering or currently using MK-677 should consult a healthcare professional. This consultation is important for discussing potential risks and benefits based on health status.
Regular monitoring of health markers, including baseline and periodic liver function tests (LFTs), is an important step for anyone using such compounds. While direct liver toxicity may be uncommon, monitoring helps detect any unexpected changes. Beyond liver health, MK-677 is associated with other common side effects, such as increased appetite and water retention, which can lead to bloating and swelling. Some individuals may also experience lethargy, tingling or numbness similar to carpal tunnel symptoms, and a decrease in insulin sensitivity. Long-term use and its full spectrum of effects remain largely unstudied in healthy individuals, emphasizing caution and medical oversight.