Grapefruit juice and some drugs don’t mix
8/4/2017, 6 a.m.
“Grapefruit juice can cause less fexofenadine to enter the blood,” decreasing how well the drug works, Huang says. Fexofenadine (brand name Allegra) is available as both prescription and OTC to relieve symptoms of seasonal allergies. Fexofenadine may also not work as well if taken with orange or apple juice, so the drug label states “do not take with fruit juices.”
Why this opposite effect? Instead of changing metabolism, grapefruit juice can affect proteins in the body known as drug transporters, which help move a drug into our cells for absorption. As a result, less of the drug enters the blood and the drug may not work as well, Huang says.
How Grapefruit Juice Affects Some Drugs
When drugs are swallowed, they may be broken down (metabolized) by enzymes and/or absorbed using transporters in cells found in the small intestine. Grapefruit juice can cause problems with these enzymes and transporters, causing too much or too little drug in the body.
Some drugs, like statins used to lower cholesterol, are broken down by enzymes. Grapefruit juice can block the action of these enzymes, increasing the amount of drug in the body and may cause more side effects.
Other drugs, like Allegra (fexofenadine) used to treat allergies, are moved by transporters into the body’s cells. Grapefruit juice can block the action of transporters, decreasing the amount of drug in the body and may cause the drug to not work as well.
Find Out if You Should Avoid Grapefruit or Other Juices
•Ask your doctor, pharmacist or other health care provider if you can drink grap- efruit juice while taking your medication.
•Read the medication guide or patient information sheet that comes with your prescription drug to find out if grapefruit juice affects your drug.
•Read the Drug Facts label on your OTC drug, which will say whether you shouldn’t have grapefruit or other fruit juices with it.
•If you must avoid grapefruit juice with your medicine, check the labels of fruit juices or drinks flavored with fruit juice to see whether they are made with grapefruit juice.
•Seville oranges (often used to make orange marmalade), pomelos, and tangelos (a cross between tangerines and grapefruit) may have the same effect as grapefruit juice. Do not eat those fruits if your medicine interacts with grapefruit juice.