Health officials have issued a stark warning about a weight-loss supplement which has been linked to liver failure and death.
Anyone who has any OxyElite Pro should not use it, the Medicines and Healthcare products Regulatory Agency (MHRA) said .
The manufacturers of the supplement, USP Labs, recently changed the ingredients of the supplement so it no longer contains DMAA - the substance linked to the death of British marathon runner Claire Squires.
The 30-year-old collapsed a mile from the finish line on April 22 last year. The hairdresser, from North Kilworth, Leicestershire, suffered cardiac failure after taking supplement Jack3D which contained 1,3-dimethylamylamine (DMAA).
However since the manufacturer changed the ingredients, there have been a number of cases of liver problems associated with the "popular" sport supplement, the MHRA said.
The reformulated product contains aegeline - a substance that has recently been linked to 56 cases of acute hepatitis in the United States, which led to two users suffering liver failure and the death of another, the MHRA spokesman said.
The medicines regulator has issued a public warning about "serious liver and heart problems" associated with two versions of OxyElite Pro.
One version of the product contains DMAA - associated with a number of side-effects ranging from shortness of breath to heart attacks.
The other version contains Aegeline, which the Food Standards Agency has recently warned against.
The MHRA has urged people not to use or buy the product and is contacting retailers to "quarantine" all available stock until authories can investigate further.
Last year the regulator took steps to remove products containing DMAA from the market.
Nimo Ahmed, the MHRA's head of intelligence for enforcement, said: "OxyElite Pro is a potentially dangerous sports supplement and people should not use it.
"We have asked retailers to quarantine any available stock while the regulatory authorities investigate further.
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"If people have questions or if they are worried that they have used this supplement, they should contact their GP or another healthcare professional."
UK Anti-Doping chief executive Andy Parkinson said: "We remind those who use supplements of the need to choose reputable manufacturers who can justify their claims with scientific evidence, and screen products to minimise the risk of a user testing positive for a substance on the World Anti-Doping Agency's prohibited list."
The American company USP Labs was not available for comment on the MHRA's damning indictment of the product.
But on October 8 it responded to concerns raised about its product, saying: "The cluster of liver issues in Hawaii is a complete mystery and nothing like this has ever been associated with OxyElite Pro in all of the years our products have been in the market.
"We know of no credible evidence linking OxyElite Pro to liver issues. The ingredients have been studied for safety, are consumed in the food supply and widely used in dietary supplements.
"Out of an abundance of caution, the company has ceased domestic distribution of OxyElite Pro with the Purple Top and OxyElite Pro Super Thermo Powder until the investigation has been completed. The company continues to believe these versions are safe and are not the cause of the cluster of liver toxicity that has occurred in Hawaii."
