LIQUORICE root capsules, a traditional remedy for coughs, colds and for hot flushes, could be dangerous for those taking medication, warn researchers.
The supplements, sold by health food shops, may prevent drugs being absorbed by the body quickly enough.
They do this by disrupting the work of enzymes in the liver, warn the scientists. This could pose a significant safety risk' for anyone on medication.
Dr Richard van Breemen, from the University of Illinois, presented his findings at a national meeting of the American Chemical Society.
He said: Consuming too much liquorice can be harmful, but we wondered whether the small amounts in dietary supplements might cause problems by interfering with drug metabolism or transportation.
The liver has enzymes that process medications, and if these enzymes are induced or inhibited, the drugs will either be processed too quickly or too slowly.'
Holland & Barrett's Good * Natural liquorice root capsules sell at £11.49 (over R186) for 100.
Users are advised to take one to two, two or three times daily, with meals or as a tea'.
Amazon has 100 capsules of Swanson Licorice Root at £8.
A spokesman for Holland & Barrett said it staff and website both offered information on the product.
He added: We advise all customers to consult a doctor before beginning a supplement regime.'
Swanson did not respond to requests for a statement, and Amazon would not comment.
© Daily Mail