Ibutamoren (MK 677) not OK - Don’t be fooled by the marketing!

  • Integrity Blog

Ibutamoren, also known as MK 677 and Nutrobal, is a substance that increases levels of Human Growth Hormone (hGH) in the body. While marketed online as a substance to ‘build muscle’, Ibutamoren is technically considered a poison. 

Ibutamoren (MK 677) Not Approved for Human Use

It is banned in sport and has a range of dangerous side effects. Worst of all, Ibutamoren has not even been approved for human use. This means there is no toxicity data and the extent of potential side effects, particularly long-term ones, remain unknown.

Reported side effects include:

  • Increased appetite
  • Swelling
  • Anxiety
  • Numbness and:
  • Muscle pain

It also causes:

  • Bone mineral density to decrease.
  • Increased fasting blood glucose and:
  • Decreased insulin sensitivity.

“Athletes who may be tempted to consider Ibutamoren use need to be aware that there are risks to their health and sporting career from its use” says Dr Naomi Speers.

Ibutamoren may seem attractive in sport but don’t be fooled - as well as the health risk, it is prohibited both in-competition and out-of-competition under the World Anti-Doping Code and is listed explicitly in the World Anti-Doping Agency (WADA) Prohibited List.

This means athletes who use, possess or supply ibutamoren to others are committing an anti-doping rule violation (ADRV) which could result in a lengthy sanction. Ibutamoren is also included in the Australian Poisons Standard. It is illegal to possess without authority.

Athletes and support people can check the status of substances in sport using the Global DRO website. Or via the free Sport Integrity app

“Sport Integrity Australia reminds athletes to check the status in sport and health risks of any substance they consider using,” Dr Speers said.

Related substance information