You might need to check with your doctor before you can enjoy your next morning grapefruit. Web MD reports more and more prescription drugs show dangerous and even fatal interactions with the popular citrus fruit.

The Canadian Medical Association Journal released findings that show more than 85 commonly prescribed medications have known side effects when combined with grapefruit products. Heart medicines, antibiotics, cholesterol medicines and cancer medicines are just some of the drugs which cause harmful interactions.

The problem comes from natural chemical compounds in grapefruit called furanocumarins, which prevent the processing of ingested medications. This can cause the amount of unmetabolized drugs in the system to grow until they reach poisonous levels.  Taking normal amounts of a medication for just a few days can quadruple the amount in the body because of this interference.

Tara Narula, a cardiac care physician at New York’s Lenox Hill Hospital, noted that many different drugs can cause the interaction and it doesn’t matter how much time passes between taking the medication and ingesting grapefruit:

Grapefruit and grapefruit products may interact with a broad class of medications ranging from cardiovascular to hormonal drugs. Some have more of an effect if you take them in close proximity to drinking grapefruit juice than if you space it out, but there can still be an interaction if you take the pill the night before or 12 hours before consuming grapefruit or grapefruit juice.

Some good news is only certain drugs interact badly with grapefruit, so a different medication targeting the same illness might offer a solution. Do not stop taking any prescribed medication unless you first consult with your doctor.