The Effects Of Grapefruit Juice On Medication

Enjoying a glass of grapefruit juice in the morning provides your body with a number of nutrients including potassium, fiber and the antioxidant vitamin C. It's also lower in calories than many other fruit juices, making it an ideal option if you are watching your caloric intake. If you take certain medications, however, consuming grapefruit may cause unsafe drug interactions.

Interaction Theory

It's unclear what substance in grapefruit is behind the possible drug interactions, although it's likely a chemical known as furanocoumarin, according to the Harvard Medical School Family Health Guide. The theory is that furanocoumarin affects the function of CYP3A4, an enzyme present in your intestines. CYP3A4 helps limit the amount of medication your intestines absorb into the bloodstream. The grapefruit chemical attaches to this enzyme, thereby blocking it and its function. This causes an excessive increase of the drug in the bloodstream at a faster rate.

Effected Medications

Grapefruit juice has the potential to indirectly interact with several types of drugs. These include medications to treat anxiety, depression, high cholesterol, hypertension and insomnia. Drugs used to prevent organ transplant rejection may also be affected. Grapefruit does not cause affect all drugs treating these conditions, but several common medications do make the list, including diazepam, zolpidem and sertraline. Cholesterol-lowering statins, such as atorvastatin and simvastatin, may also be affected.

Signs and Symptoms

Boosts in drug levels in your body may not necessarily be substantial enough to cause symptoms. Reactions vary depending on the medication, but increased drug amounts circulating in the bloodstream may cause headaches, upset stomach, an irregular heartbeat and fatigue, according to a August 2006 article appearing in the journal, "American Family Physician." More severe effects are possible as well, such as liver damage, kidney toxicity, low blood pressure and thyroid toxicity. Interactions with calcium-channel blockers, typically used to treat high blood pressure, have resulted in heart attacks in rare cases.

Recommendations

Avoid consuming pomelos and Seville oranges if you're taking a medication that may interact with grapefruit juice, as these may also affect the intestinal enzyme he same way. Enjoying other citrus fruits is considered safe, so you may want to consider replacing your grapefruit juice with other options. You can also discuss with your doctor switching to another medication that won't cause these potentially dangerous reactions. Keep in mind that spacing out when you consume grapefruit juice and when you take your medications will likely not prevent interactions from occurring. The authors of the "American Family Physician" point out that grapefruit's interaction with CYP3A4 may persist up to 72 hours after you consume it.