A number of unlicensed traditional Chinese medicines have been found to contain dangerously high levels of lead, mercury and arsenic.
Bak Foong Pills, used for the treatment of menstrual pain, have been recalled in Hong Kong after it was found to contain two times the permitted level of lead.
And Hairegenerator, another traditional Chinese medicine, has been found to contain 11 times the permitted level of mercury.
There are extremely high levels of arsenic in a product going by a variety of names, including Niu-Huang Chieh-tu-pein, Divya Kaishore Guggul and Chandraprabha Vati.
Although these products are not authorised for sale in the UK, they are available to buy on the internet.
People have been warned to exercise extreme caution when buying unlicensed medicines as they have not been assessed for safety.
Richard Woodfield, MHRA’s Head of Herbal Policy said: “Natural does not mean safe. The adulteration of traditional Chinese medicines with heavy metals is a significant international problem and can pose a serious risk to public health.”