Dear Doctor Column, August 16, 2004

Grapefruit Interacts With Many Medications

Question:

I heard you shouldn't take certain medications with grapefruit juice. Why not?

Answer:

Grapefruit juice is the juice of choice for many households, containing compounds that may help decrease the risk of heart disease and cancer, as well as calcium to help strengthen bone. It also carries the American Heart Association's "seal of approval."

However, if you are taking certain medications mentioned below, check with your doctor before eating grapefruit or consuming its juice. When taking these medicines, grapefruit juice may interfere with your body's ability to absorb, process, and properly get rid of the medicine. This may cause a buildup of medication in your body, so you could essentially "overdose," greatly increasing your risk of dangerous side effects, such as an abnormal heart rhythm, muscle damage, and even death.

Grapefruit juice contains plant chemicals called flavonoids, which can inhibit enzymes or other substances in the body that are needed to break down medications. Drugs that grapefruit juice may affect include: selected calcium channel blockers (a common type of blood pressure drug); lipid-lowering statins (for high cholesterol levels); sedatives; the immunosuppressant cyclosporine (taken by people who have undergone an organ transplant), and a few other medications.

If you are taking any of these types of drugs and drinking grapefruit juice, ask your doctor or pharmacist whether to steer clear of grapefruit. Also, ask about drinking mixed juices that contain grapefruit juice.

A February 2004 medical journal article in Neurology, featured a case report on a woman who had been taking simvastatin (Zocor) for 2 years with no side effects. But 4 days after she began eating a whole grapefruit every morning for breakfast, she developed muscle pain and weakness. Tests revealed her muscles were slowly disintegrating, a condition known as rhabdomyolysis, which is a potentially fatal complication of statin use.

So, even if you have taken certain medications with grapefruit juice in the past and had no adverse effects, you should not assume it is safe to continue to do so.

Always check with your doctor before stopping or changing the way you take your medicine.