Doctors have warned of a “lack of knowledge” about the dangers of mixing some medications with grapefruit.
The fruit can cause overdoses of some drugs by stopping the medicines being broken down in the intestines and the liver.
The researchers who first identified the link said the number of drugs that became dangerous with grapefruit was increasing rapidly.
They were writing in the Canadian Medical Association Journal.
The team at the Lawson Health Research Institute in Canada said the number of drugs which had serious side effects with grapefruit had gone from 17 in 2008 to 43 in 2012.