Grapefruit juice is a healthy beverage, full of essential vitamins and minerals. But for some people, grapefruit juice can cause dangerous and even life-threatening interactions with medications. Grapefruit juice may cause adverse side effects with over 50 different medications. In particular, patients taking cholesterol-lowering drugs are at risk.
Cause
Grapefruit juice interacts with many medications because it is broken down by the same liver enzyme that metabolizes the drugs. This enzyme, called cytochrome P450 3A4 or CYP3A4, may become completely bound to grapefruit juice, leaving no available enzyme to break down the drug compound. As a result, the medication may accumulate at dangerously high levels in the body.
Amounts
Harvard Medical School notes that even a small amount of grapefruit juice may have potent effects. One glass of the juice may reduce the levels of the CYP3A4 enzyme by as much as 47 percent. Furthermore, the effect of grapefruit juice lasts long after the juice has been consumed. One-third of the effect is still present after 24 hours. For this reason, grapefruit juice may have serious effects even when you drink it at a separate time from your medication. Instead, you will likely need to avoid grapefruit juice completely.
Signs
The symptoms of a drug interaction with grapefruit juice vary depending on the medications involved. In the case of cholesterol-lowering drugs, signs of adverse interaction may include muscle pain, fatigue and fever. In severe cases, the high amounts of circulating drug cause muscle fibers to break down and induce kidney failure. A drug interaction requires immediate emergency medical attention and may be life-threatening.
Drugs
Read the warning labels that come with your prescription and talk to your doctor of pharmacist if you are unsure about the safety of your medication and grapefruit juice. Several drugs in the statin family of cholesterol-lowering medication are affected by grapefruit juice. These include atorvastatin, simvastatin and lovastatin, sold under the brand names Lipitor, Zocor and Mevacor, respectively.
