Grapefruit and Drug Interactions
~ October 2000 No.115 ~
We usually think of foods being good for our health, but there are exceptions. Some people have sensitivity to such things as peanuts, shell fish and certain mushrooms. Exposure to even very small amounts of these foods can result in anaphalactic shock which can be life threatening. For others a case of itchy hives can follow a dish of fresh strawberries - a minor and short lasting inconvenience. Bloating, excessive gas and digestive upsets are sufferd by some after a meal that contains beans or perhaps cucumber.
Yes, foods themselves can cause problems, but some foods can also interact with drugs affecting drug metabolism and potency. Medical doctors and pharmacists often caution their patients about side effects of drugs. However, a relatively new phenomenon has developed, in which one food in particular - grapefruit - may negatively affect us in perhaps an unexpected way.
Eating grapefruit has been shown to affect the activity of some intestinal and liver enzymes. The way in which grapefruit affects these enzymes is not clear. However, this effect on enzymes can affect metabolism in general and the speed at which the body metabolizes drugs in particular. This can cause a rise in the concentration of the drug in the blood stream which affects the action of the drug. The effects of the juice vary depending on whether the drug is swallowed, injected intravenously or applied externally (by patch).
More and more health professionals are telling their patients to not eat grapefruit or drink grapefuit juice during the period of their medication. A consumption as low as 250 ml of juice can cause concern. Consuming grapefuit juice regularly may make the problem worse. What about other citrus fruits? It seems that orange juice does not have the same effect.
It is always a good idea to ask as many questions about possible interactions and side effects as you can about treatments perscribed by a medical doctor. If you regularly consume grapefruit products, it may be important to share this with your doctor.
|Note: other drugs are being investigated; this list may not be complete|
Drug Administration and Grapefruit Juice.