Although grapefruits and grapefruit juice can be an important part of a nutritious diet, they may also interact with a number of commonly used medications. These interactions can alter blood levels of these drugs and potentially cause dangerous side effects. Fortunately, there are equivalent alternatives to many of the medications that interact with grapefruit.
Grapefruit and Medications
According to the Harvard Medical School Family Health Guide, it is not certain which chemicals in grapefruit cause drug interactions, but it may be furanocoumarin, which binds to an intestinal tract enzyme called CYP3A4 which can reduce the absorption of some medications. When the CYP3A4 enzyme is blocked by the chemicals in grapefruit, medication can pass more easily from the stomach into the bloodstream. Blood medication levels will then rise higher and more quickly than normal, and these abnormally high levels can be potentially dangerous.
Which Medications Are Affected?
Medications that may interact with grapefruit juice include some calcium channel blockers (used to treat high blood pressure and angina), some statins (used to treat high cholesterol), immunosuppressants (used by transplant patients to prevent rejection), benzodiazepines (used for anxiety and insomnia), and several other neurological and psychiatric medications, including some antidepressants.
What Can Happen?
As little as one glass of grapefruit juice can reduce CYP3A4 by 47 percent. The resulting increased drug absorption and the corresponding increased drug effects can lead to side effects or adverse reactions. Whether a person will experience such reaction depends on a variety of factors, including the genetics of the individual, the type of medication taken, the dosage of the medication, and the amount of grapefruit consumed, according to the Center for Drug Interaction Research and Education.
Non-interacting Alternative Medications May Be Available
If you'd rather not give up grapefruit, there may be an alternative to your medication that will not pose a risk of interaction. The blood pressure medications amlodipine, verapamil and diltiazem have little or no interaction with grapefruit juice. Neither do the cholesterol medications fluvastatin, pravastatin or rosuvastatin. There are also alternatives to the psychiatric medications that interact with grapefruit. Your health care provider should be able to tell you your options.
Other options
Other options that may help avert a potentially dangerous interaction between grapefruit and your medication include switching to orange or some other type of juice, reducing your consumption of grapefruit, and avoiding ingesting grapefruit and your medication simultaneously. The effect of grapefruit on medication levels lessens over time, although some level of interaction can persist for as long as 24 hours.
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