As many as 84 sports supplements have been banned from the shelves of British shops because they contained illegal drugs, regulators announced yesterday.
Regulators say they expect to find more as manufacturers seek to exploit Olympic fever to sell get-fit-quick products.
As well as drugs such as steroids and hormones investigators are searching for dangerous herbal extracts such as ephedrine, synephrine and yohimbine.
Banned products include energy and muscle gain products.
One substance called Celtic Dragon put two men in hospital with severe jaundice and liver damage. It contained adulterated steroids.
The Medicines and Healthcare products Regulatory Agency urged the public to be careful of products purchased.
David Carter, of the MHRA, said: "People need to be aware that buying illegal sports supplements can seriously damage your health. The products may claim to boost your energy or muscle but they could contain unapproved ingredients that can
cause kidney failure, heart problems or seizures.
"We recommend that people only use approved products and speak to a qualified medical practitioner if they have any concerns about any supplements they may be taking."
Andy Parkinson, chief executive of UK Anti-Doping said: "Elite athletes need to exercise extreme caution when it comes to deciding what they put into their body and a vital part of our prevention programme is educating athletes in the risk of supplements.
"Athletes who use sports supplements need to choose reputable manufacturers who can justify their claims with scientific evidence, and have their products screened to minimise the risk of testing positive for a substance on the World Anti-Doping Agency's Prohibited List."