MK-677 side effects and risks

Reported side effects

• Increased hunger: 29/43, 67%, versus 8/22, 36%, placebo in the older adult trial., mild. Track appetite and weight; persistent unwanted hunger needs review. (source)
• Leg swelling or water retention: 19/43, 44%, versus 6/22, 27%, placebo., moderate. New swelling needs review. Breathlessness or rapid weight gain needs urgent care. (source)
• Muscle pain: 14/43, 33%, versus 2/22, 9%, placebo., mild. Review persistent pain; pain plus marked swelling needs prompt assessment. (source)
• Joint pain: 25/43, 58%, versus 17/22, 77%, placebo. It was not more frequent on MK 677., moderate. Two treated women reduced dose for joint pain and later withdrew. (source)
• Higher blood sugar or HbA1c: Fatty liver pilot: 4/12, 33.3%; no concurrent control. Alzheimer trial: glucose rise 15.4% versus 4.6% placebo., moderate. Check glucose and HbA1c; thirst and frequent urination need prompt review. (source)
• Heart failure: Hip fracture trial: 4/62, 6.5%, versus 1/61, 1.7%, placebo; trial stopped early., serious. Stop and seek urgent care for breathlessness, chest pain or rapidly worsening swelling. (source)
• Higher blood pressure: Hip fracture trial: mean systolic rise 11.9 16.4 mmHg versus 2.3 to +2.3 placebo across visits., moderate. Monitor blood pressure and fluid gain; persistent elevation needs review. (source)
• Liver injury or raised liver enzymes: One 2025 case after 2 months; reversible enzyme rises also occurred in trials. General incidence is unknown., serious. Stop and get prompt care for yellow skin, dark urine or persistent upper-belly pain. (source)
• Tiredness or sleepiness: Reported in Alzheimer trial drug related events and community use; reliable individual event rates unavailable., moderate. Review new daytime sleepiness; avoid driving while sleepy. (source)
• Numbness or carpal-tunnel symptoms: Reported in trial safety summaries; reliable overall rate unknown., moderate. Persistent tingling, weakness or hand pain needs review. (source)

Stop and get help if

• Breathlessness, chest pain, fainting or swelling with rapid weight gain: Stop use and get urgent medical care now.
• Severe thirst, frequent urination, vomiting, deep breathing or confusion: Check glucose if available and get urgent care. Severe symptoms need emergency assessment.
• Yellow skin or eyes, dark urine or persistent upper-belly pain: Stop use and seek prompt medical assessment for possible liver injury.
• Severe headache with vision change or vomiting: Get urgent assessment. Raised pressure around the brain is a GH-class concern.
• Face or throat swelling, trouble breathing or collapse: Call emergency services now.
• Sudden severe left-sided belly pain with dizziness or fainting: Get emergency care. A mixed-use case reported spleen rupture; causation remains unproven.
• Low glucose with confusion, seizure or fainting while using diabetes medicines: Get emergency help. Starting or stopping a glucose-altering drug can change medicine needs.

Who should avoid it

• under18: Pediatric studies require specialist trial care. They do not establish safe self-use in minors.
• pregnant: No established pregnancy safety; pregnancy was excluded from the adult liver trial.
• breastfeeding: Milk transfer and infant safety are unknown; breastfeeding was excluded from the adult liver trial.
• tryingToConceive: Reproductive safety is unknown. Trial contraception rules are a research safeguard, not proof of safety.
• activeCancer: It raises GH and IGF-1. Avoid with active cancer; this screen extrapolates from GH treatment guidance.
• cancerHistory: Review past cancer with the treating team. MK-677 trials cannot establish recurrence safety.
• heartCondition: Fluid retention may worsen heart disease. A hip-fracture trial stopped over heart-failure concerns.
• other: The heart-failure signal and fluid retention make further exposure unsafe without assessment.
• diabetes: Blood sugar can rise and insulin sensitivity can fall, even when fasting glucose initially looks normal.
• diabeticRetinopathy: Active severe eye disease needs specialist review. This is a GH-class precaution, not a measured MK-677 risk.
• uncontrolledBloodPressure: Blood pressure rose in the hip-fracture trial; fluid retention adds concern.
• kidneyDisease: A small dialysis study is not proof of kidney safety. Fluid balance and drug handling need review.
• liverDisease: Liver injury has been reported. Safe dose changes for liver disease are not established.
• surgeryPlanned: Tell the surgical team about use. Glucose and fluid shifts matter around surgery.
• testedAthlete: WADA prohibits ibutamoren at all times under S2.2.4 in the 2026 list.
• pancreatitisHistory: Pancreatitis is a GH-treatment warning; FDA flags possible class risks for MK-677. Direct ibutamoren risk is unmeasured.
• other: Insulin sensitivity can worsen before fasting glucose changes. Mixed-use diabetes cases included people with prior metabolic risk.

Interactions

• Insulin: Reduced insulin sensitivity may change insulin needs. This is a GH-class concern; direct MK-677 interaction trials are lacking.
• Sulfonylureas: Glucose control may worsen. Changing or stopping MK-677 may change medicine needs; do not adjust doses from forum advice.
• Other GH secretagogues, growth hormone or IGF-1: Duplicate growth signals may add swelling and glucose effects. Combination efficacy and safe doses are not established.
• SARMs and anabolic steroids: Mixed-use reports show liver, lipid and hormone harms. Unknown product contents can add further drugs.
• Berberine and self-added glucose-lowering products: Forum use does not prove protection from insulin resistance. Added glucose-lowering products can complicate glucose management.
• Systemic corticosteroids: Both can worsen blood sugar. GH can also alter steroid replacement needs; this is class-based, not a proven MK-677 interaction.
• Anticoagulants: CYP or P-glycoprotein effects could change some anticoagulant levels. This is a lab-based concern; clinical interaction size is unknown.
• CYP3A inhibitors and grapefruit: May raise ibutamoren exposure. Trial protocols excluded moderate or strong CYP3A inhibitors and prohibited grapefruit; clinical effect sizes are unknown.
• CYP3A inducers: May lower exposure. Trial protocols excluded strong CYP3A inducers; no validated compensating dose change exists.
• Sensitive CYP substrates: Ibutamoren induced several CYP enzymes in lab tests. Trial protocols restricted sensitive substrates; actual clinical level changes are unknown.

Product quality risks

• TGA testing in June 2026 found an undeclared anabolic steroid in tested MK-677 capsules.
• A 44-product internet survey found 25% with unlisted drugs and 59% with amounts differing from labels. These were mixed performance products, not 44 MK-677 products.
• A separate 60-supplement study detected undeclared MK-677 in some products. It did not establish a market-wide contamination rate.
• A 2025 official-laboratory survey covered 324 samples; ibutamoren was among the five most frequent drugs. Some quantified products were overdosed.
• Identity, dose, impurities and contamination cannot be inferred from appearance or a research-use label.
• FDA records December 2025 warning letters concerning ibutamoren products in its supplement-ingredient directory.