Grapefruit juice is rich in vitamin C and can be a healthy way to start your day. But grapefruit juice can also be dangerous when taken with many common medications, including antidepressants, blood pressure and cholesterol medications, and drugs used to treat cancer and allergies. More than 50 drugs interact with grapefruit juice, according to a report in ScienceDaily.
Background
Many foods have the potential to interact with medications, but grapefruit juice is one of the worst offenders. The same liver enzyme that breaks down many drugs is also the one that metabolizes grapefruit. The cytochrome P-450 3A4 enzyme helps convert grapefruit juice into components that the body can use. Grapefruit contain hundreds of chemicals and doctors aren't sure which one causes the interaction. Furanocoumarin is the prime suspect. It is also found in tangelos and Seville oranges, so the guidelines regarding grapefruit should also apply to those fruits.
Tragedy
Cholesterol drugs are especially dangerous with grapefruit. The liver can become overwhelmed processing the juice, allowing the medication to build to toxic levels. Kidney failure can result. This is what happened to one patient, according a ScienceDaily report on a December 2004 study in the "American Journal of Nursing." The patient was taking atorvastatin and moved to Florida for the winter and began drinking two or three glasses of grapefruit juice daily. Two months later he went into kidney failure and died.
Medication Warnings
Other drugs to be aware of mixing with grapefruit juice include plendil, procardia, simvastatin, valium, versed, sandimmune, sertraline and buspar. This list is not inclusive; many drugs have a lesser interaction with grapefruit juice. Even a small amount of juice can be dangerous. One glass causes a 47 percent reduction of the intestinal enzyme that regulates absorption, according to Harvard Medical School. This effect wears off slowly -- a third of its impact remains after 24 hours.
Safety Tips
If you take any prescription medications, do not take any grapefruit products or consume citrus without consulting your physician or pharmacist for possible interactions. Don't assume that you can just take the medicine and grapefruit juice at different times; an interaction can still occur. Certain foods, such as marmalades, may contain Seville oranges and can trigger an interaction.
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