Interesting info
Here’s what happens: Grapefruit contains furanocoumarins, which block an enzyme that normally breaks down certain medications in the body. When it is left unchecked, medication levels can grow toxic in the body.
This interaction can occur even if grapefruit is eaten many hours before taking the medication. For example, simvastatin, when taken with about a 7-ounce glass of grapefruit juice once a day for three days, produced a 330% greater concentration of the drug compared to taking it with water. This can cause life-threatening muscle damage called rhabdomyolysis.
“Grapefruit and grapefruit products may interact with a broad class of medications ranging from cardiovascular to hormonal drugs,” says Tara Narula, MD, the associate director of cardiac care at Lenox Hill Hospital in New York City. “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.”
The researchers note that grapefruit interaction is specific to certain drugs and doesn’t necessarily affect an entire drug class.