I like to drink grapefruit juice but hear that it can interfere with some prescription medications. Is that true?

Answers from Katherine Zeratsky, R.D., L.D.

Yes. Grapefruit and certain other citrus fruits and products can interfere with several kinds of prescription medications.

Don't take these interactions lightly. Some can cause potentially dangerous health problems. Check with your doctor or pharmacist before consuming any citrus products, including grapefruit, if you take prescription medications.

You may need to eliminate grapefruit products from your diet. Simply taking your medication and grapefruit product at different times doesn't stop the interaction.

Problems arise because chemicals in the fruit can interfere with the enzymes that break down (metabolize) the medication in your digestive system. As a result, the medication may stay in your body for too short or too long a time. A medication that's broken down too quickly won't have time to work. On the other hand, a medication that stays in the body too long may build up to potentially dangerous levels.

The list of medications that can interact with grapefruit is long and includes commonly prescribed medicines that:

  • Fight infections — erythromycin
  • Reduce cholesterol — atorvastatin (Lipitor), lovastatin (Altoprev), others
  • Treat high blood pressure — felodipine, carvedilol (Coreg), others
  • Treat heart problems — amiodarone (Coradarone, Pacerone)
  • Treat depression — diazepam (Valium, Diastat), fluvoxamine, others
  • Prevent organ rejection in transplant recipients — cyclosporine (Sandimmune, Neoral, others), tacrolimus (Prograf, Astagraf), others

In addition, researchers have identified other fruits and juices that may interact with medications. This is because many citrus varieties are grafted on a grapefruit stem. Tangelos (Honeybell and Minneola) are tangerines crossed with grapefruit. Seville oranges and their juice should also be avoided if you take medication that interacts with grapefruit.

Another potential problem is that some products may contain grapefruit but don't say so in the name or on the ingredients list. For example, numerous "citrus" flavored soft drinks have been identified as possibly containing grapefruit juice or grapefruit extract.

Play it safe with prescription drugs. Always ask your doctor or pharmacist when you get a new prescription if it interacts with any foods or other medicines. If the answer is yes, ask whether you need to eliminate that food from your diet.

Dec. 07, 2015 See more Expert Answers