Regulators warn that many of us believe that "herbal" is synonymous with "safe", whereas herbal remedies can be deadly.

"There's a risk that the herbal remedy will react with any prescription drugs. They're also more vulnerable to fraudulent, even criminal operators who put products out which are heavily adulterated with dangerous pharmaceuticals."-says Richard Woodfield, Head of Herbal Policy at the Medicines and Health care products Regulatory Agency (MHRA).

In April, an MHRA investigation into Jia Ji Jian, sometimes marketed as 'herbal Viagra', revealed it contained up to four times the level of pharmaceuticals found in legally prescribed anti-obesity and anti-erectile dysfunction medicinal products, which can cause serious side effects including heart and blood pressure problems. As a herbal remedy it should not contain any pharmaceuticals at all.

MHRA information line: 020 7084 2000; www.mhra.gov.uk