Drug Interactions with Grapefruit Juice
Grapefruit juice drug interactions can be researched with our drug interactions checker.
While grapefruit is a nutritious fruit, many patients are concerned about the potential for drug interactions with grapefruit juice. Patients may receive a medication prescription container with an affixed warning label that recommends to avoid grapefruit or grapefruit juice while taking the medication.
Are drug interactions with grapefruit juice clinically significant?
Grapefruit juice affects how drugs are changed in the body for eventual elimination.
Drugs or toxins are broken down (metabolized) so that they can be eliminated from the body.
Grapefruit juice decreases the activity of the cytochrome P450 3A4 (CYP3A4) enzymes that are responsible for breaking down many drugs and toxins. Grapefruit contains compounds known as furanocoumarins that block the CYP3A4 enzymes. When grapefruit juice is consumed, the enzyme’s ability to break down the drug for elimination is decreased. Blood levels of the drug may rise, resulting in the risk for new or worsened side effects.
Will taking medications at different times reduce interactions?
Taking medications at a different time from when grapefruit juice is consumed will not prevent the interaction.
The effects of grapefruit juice on certain medications can last for over 24 hours. So, even if the medicine is taken only once per day, grapefruit and grapefruit juice should still be avoided for the entire treatment period.1 In some cases, patients may be able to drink smaller quantities of grapefruit juice, so patients should follow the directions on the patient information leaflet for each individual drug or ask their health care provider.
What about other types of juice?
Other kinds of fruit juice may rarely interfere with medications, but for most medications, orange juice, or other kinds of juice like apple or grape, can be consumed instead of grapefruit juice.
Fexofenadine (Allegra), a popular non-drowsy antihistamine available over-the-counter (OTC) can interact not only with grapefruit juice, but also with apples and orange juice. However, in the case of fexofenadine, blood levels of the drug go down and the effectiveness of the antihistamine may be reduced. This interaction occurs by a different mechanism than CYP450 3A4, but nonetheless, it is recommended that fexofenadine be taken with water, and not fruit juice.2
Talk to your healthcare provider
When new medications are started it is important to check for potential drug interactions and consult with a health care provider. Warnings labels on prescription bottles should be followed. If an interaction is found to occur, it may be possible that an alternative medication can be prescribed, and the interaction can be avoided.
Common drug/grapefruit interactions
Examples of some of the most common or serious grapefruit juice drug interactions:
- fentanyl transdermal system
Grapefruit juice drug interactions can be researched here.
Watch our mini video series on Grapefruit interactions:
- Bailey DG, Malcolm J, Arnold O, et al. Grapefruit juice-drug interactions. Br J Clin Pharmacol 1998;46:101-110.
- Horn J, Hansten P. Fruit Juice Interactions. Pharmacy Times. Published Online Dec 1, 2005
Last updated: 2014-05-28 by Leigh Anderson, PharmD.