The number of drugs when mixed with grapefruit that can lead to serious health problems, including sudden death, has skyrocketed, warns a Canadian researcher who first discovered the toxic link.

Some of the drugs known to interact with grapefruit include anti-cancer agents, heart drugs, pain medications and drugs to treat schizophrenia

In an article in the Canadian Medical Association Journal, David Bailey, a scientist at the Lawson Health Research Institute in London, Ontario, said more than 85 drugs, many of them highly prescribed for common medical conditions, are known to interact with the pink fruit.

He first made the link 20 years ago. But the number of medications with the potential to interact with grapefruit and cause serious adverse health effects has jumped from 17 to 43 in the last four years, as new drugs have been rolled out, Bailey said.

“How big a problem are such interactions? Unless healthcare professionals are aware of the possibility that the adverse event they are seeing might have an origin in the recent addition of grapefruit to the patient’s diet, it is very unlikely that they will investigate it,” Bailey said.

Generally patients do not say they eat grapefruit and doctors do not ask, he lamented in the article.

Grapefruit poses a risk when mixed with certain drugs because it inhibits an enzyme that metabolises ingested drugs, resulting in the drugs entering the bloodstream at full force, which can lead to overdosing.

Some of the drugs known to interact with grapefruit include anti-cancer agents, heart drugs, pain medications and drugs to treat schizophrenia. All of them are administered orally.

It does not take much grapefruit to have an effect. Drinking a single glass of grapefruit juice with medication can lead to serious side effects, including gastrointestinal bleeding, kidney failure, breathing problems and sudden death.

Other citrus fruits such as Seville oranges and limes can have similar effects. But they have been studied less.