Doctors have issued a warning about mixing grapefruit consumption with certain types of medication.
The fruit can prevent the body from breaking down the medicines, thus potentially causing overdose.
Researchers who first identified the link with the fruit and such problems say that the number of associated drugs is rising rapidly.
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.
They include some drugs for a range of conditions including blood pressure, cancer and cholesterol-lowering statins and those taken to suppress the immune system after an organ transplant.
Furanocoumarins, a naturally occurring chemical in grapefruit is responsible for stopping the drugs breaking down, meaning that more medicine than can be tolerated reaches the digestive system.
Three times the levels of one blood pressure drug, felodipine, was reported after patients had a glass of grapefruit juice compared with a glass of water.
Dr David Bailey, one of the researchers, said, "One tablet with a glass of grapefruit juice can be like taking five or 10 tablets with a glass of water and people say I don't believe it, but I can show you that scientifically it is sound."
Other citrus fruits can have the same effect.
