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Grapefruit and Drug Interactions

Doctorpedia Editorial Team Doctorpedia Editorial Team May 12, 2020
Medically reviewed by Susan Kerrigan, MD and Marianne Madsen

Grapefruit is a popular citrus fruit usually enjoyed with breakfast that offers many health benefits. It contains antioxidants, vitamins A and C, and boosts your immune system. But if you happen to be taking any prescription drugs, you might want to rethink that morning glass of grapefruit juice.

 

Why? Because the fruit is notorious for interfering with a myriad of prescription medications, including common drugs like the anti-anxiety medication alprazolam (Xanax) and the erectile dysfunction pill sildenafil (Viagra). The side effects of consuming grapefruit range from mild to severe, depending on the drug you’re taking. Some side effects may include:

 

  • Abnormal heartbeat
  • Stomach bleeding
  • Muscle pain
  • Muscle breakdown
  • Kidney damage
  • Low blood pressure
  • Trouble breathing
  • Sedation
  • Dizziness

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If you’re taking any of the medications listed below, avoid consuming grapefruit in any form. Also, if you drink a certain kind of fruit juice, check the ingredients to make sure it doesn’t contain grapefruit. Note that this is not a complete list of medications that interact with grapefruit. If you’re taking a drug that isn’t on the list, find out if it can cause any potential side effects when taken with grapefruit.

 

  • Aliskiren (Tekturna) – also interacts with apple juice, orange juice
  • Alprazolam (Xanax)
  • Amiodarone (Pacerone)
  • Atorvastatin (Lipitor)
  • Carbamazepine (Tegretol)
  • Cilostazol (Pletal)
  • Clarithromycin (Biaxin)
  • Cyclosporine (Gengraf, Neoral)
  • Colchicine 
  • Dronedarone (Multaq)
  • Erythromycin (E.E.S., Eryped)
  • Felodipine (Plendil)
  • Fentanyl  
  • Fentanyl transdermal system (Duragesic Skin Patch)
  • Fexofenadine (Allegra)
  • Flibanserin (Addyi)
  • Indinavir (Crixivan)
  • Loratadine (Claritin)
  • Losartan (Cozaar)
  • Lovastatin 
  • Nilotinib (Tasigna)
  • Naloxegol (Movantik)
  • Palbociclib (Ibrance)
  • Pazopanib (Votrient)
  • Pimozide (Orap)
  • Ranolazine (Ranexa)
  • Saquinavir (Invirase, Fortovase)
  • Sildenafil (Revatio, Viagra)
  • Simvastatin (Zocor)
  • Tadalafil (Adcirca, Cialis)
  • Vardenafil (Levitra, Staxyn)
  • Verapamil (Calan, Calan SR)
  • Warfarin

 

You may wonder why and how exactly grapefruit interacts with so many medications. Well, grapefruit can alter certain enzymes in the body, changing the effects of medications while they’re still at work. Specifically, by causing the cytochrome P450 3A4 (CYP3A4) enzymes responsible for metabolizing (breaking down) drugs to operate at a decreased level. Grapefruit contains specific compounds called furanocoumarins that prevent the CYP3A4 enzymes from doing their job. If a person consumes grapefruit while taking a prescription drug, the drug can become more potent, causing potentially toxic levels of the substance to accumulate in their blood.

 

Additionally, certain drugs interact with grapefruit in a different way. Fexofenadine (Allegra), for example, works in the body via transporters rather than enzymes. Grapefruit can also block the effects of transporters, decreasing the amount of certain drugs in the bloodstream, which can lead to diminished effects of the drug or no effects at all. 

 

If you’re prescribed any type of medication at all, ask your doctor about potential interactions with grapefruit or grapefruit juice.

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