The Medicines and Healthcare products Regulatory Agency (MHRA) has urged athletes to steer clear of the potentially dangerous ingredient DMAA, otherwise known as Methylhexanamine.

DMAA can be found in unlicensed medicines marketed as sports supplements and it has been linked with high blood pressure, tightening in the chest, strokes, heart attacks and even death.

The warning from MHRA has been issued as a significant number of products containing DMAA continue to be found on sale in the U.K.

MHRA has launched a ‘Week of Action’ between Jan. 30 and Feb. 5 supported by a number of leading national organizations to alert people to the potential dangers.

The Week of Action aims to improve awareness and includes an animated social media campaign, health & fitness bloggers sharing their stories and a video featuring Team GB Olympic weightlifters at the National Sports Stadium in Crystal Palace.

Named on the World Anti-Doping Agency’s (WADA) Prohibited List, DMAA is banned during sports competition and the safety concerns are well documented.

When MHRA finds unlicensed medicinal products containing DMAA on the market, urgent action is taken to remove them from sale. Last year MHRA took urgent action to remove a number of products containing DMAA from the market.

“As always, we will continue to take robust action when unlicensed medicinal products containing DMAA come to our attention,” said MHRA Medicines Borderline Section Manger Dr. Chris Jones. “We first removed these products from sale in 2012, and will protect public health by continuing to do so. Although the sale of DMAA products has dropped since 2012, any companies selling this unlicensed medicine is one company too many.”

Dr. Adam Carey, Chair of the European Specialist Sports Nutrition Alliance (ESSNA) said: “We fully support the MHRA’s efforts to raise awareness of the dangers of supplements which contain DMAA. MHRA has classified such products as medicinal products and they have no place in legitimate sports nutrition supplements. The dangers of consuming DMAA are significant and well-proven. We urge all sportspeople to avoid it at all costs—and emphasize that sportsmen and women can only do this by making sure they’re only buying their sports supplements from responsible and reputable retailers.