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Drug Interactions with Grapefruit Juice

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on March 10, 2024.

There are many common drug interactions with grapefruit juice. Medicines that can interact include certain cholesterol medicines, antihistamines, migraine treatments or even cancer therapies. If you eat grapefruit or drink the juice, review your medications with a healthcare provider to rule out this common drug-food interaction. 

It may also be helpful to research possible drug interactions using the Drugs.com Drug Interaction Checker. Check with your pharmacist or doctor to discuss any interactions you may find.

Follow along in this article to review common drug interactions with grapefruit juice, why and how this happens, any side effects, and if other juices, like apple or orange juice, are a problem too.

Which drugs interact with grapefruit juice?

Grapefruit is a nutritious fruit full of vitamin C, but many patients are concerned about the possibility of drug interactions. Maybe you've receive a pharmacy bottle with a warning label that recommends you avoid grapefruit or grapefruit juice while taking a certain medication. Grapefruit juice can even interact with some over-the-counter (OTC) drugs.

Examples of common medications that may interact with grapefruit juice include:

Other kinds of juice besides grapefruit juice may also interfere with medications, although this is less common. Other juices, like apple, orange, and pomegranate have also been found to interact in some cases. 

See: List of Common Drugs That Interact with Grapefruit Juice

Why does grapefruit interact with drugs?

Grapefruit juice can change how drugs are changed (metabolized) in the body for eventual elimination. This may change the amount of drug in your blood, and can lead to increased side effects or reduced drug effectiveness.

Drugs or toxins are usually broken down (metabolized) so that they can be eliminated from the body. Grapefruit or grapefruit juice can alter enzymes in the body and affect how drugs are changed in the body before they are eliminated. Specifically, 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 these CYP3A4 enzymes. When grapefruit juice is consumed, the enzyme’s ability to break down the interacting drug for elimination is decreased. Blood levels of the drug may rise, resulting in a risk for new or worsened side effects or drug toxicity. 

One whole fruit or 200 milliliters of grapefruit juice (just less than one cup) can block the CYP3A4 enzymes and lead to toxic blood levels of the drug. In rare cases, blood levels of a drug may decrease, reducing it's effectiveness.

Not all drugs in any one drug class usually have a grapefruit interaction, so your doctor can select an alternative medication if needed. In some cases, they may just adjust your drug dose.

If you drink grapefruit juice, always have your pharmacist check for drug interactions with your medications to rule out an interaction. Tell your healthcare providers about the medicines you take, including prescription, over-the-counter, herbal and dietary supplements. Don't stop any medicines until you talk to your healthcare provider.

What side effects are possible?

Side effects can vary based on the interacting drug. Side effects can range from abnormal heart rhythms, stomach upset or bleeding, muscle pain or breakdown, kidney damage, low blood pressure, difficulty breathing, sedation, and dizziness.

Other reactions may occur -- it depends on the drug and the levels of the drug in the blood.

If you have been warned about a possible drug interaction with grapefruit, ask your healthcare provider to describe the possible side effect and learn how to recognize it. 

Can I just take my medicine at a different time from grapefruit juice?

Taking medications at a different time from when grapefruit or the juice is consumed will not usually prevent the interaction, but it really depends on your drug. For example, it's best to avoid grapefruit juice with buspirone (Buspar), a medicine used to treat anxiety, but if this is not possible, the Buspar dose should be taken at least 2 hours before or 8 hours after grapefruit or grapefruit juice.

The effects of grapefruit on some medicines can last for over 24 hours. So, even if you take a medicine that is given only once per day, grapefruit and grapefruit juice may need to be avoided for the entire treatment period.

In some cases, you may be able to drink smaller quantities of grapefruit juice, or just maintain the current level of grapefruit juice you drink now without any big changes, so follow the directions on the patient information leaflet for each individual drug or ask your pharmacist or other healthcare provider.

Check the food ingredient labels more closely if you need to avoid grapefruit completely. For example, citrus-flavored soft drinks may contain grapefruit juice or grapefruit extract.

What other types of juice interact with drugs?

For most medications, orange juice, apple juice, or grape juice can be consumed instead of grapefruit juice without any concern for an interaction. But in some cases, orange or apple juice can infrequently cause an interaction, like with fexofenadine (Allegra), an OTC antihistamine or aliskerin (Tekturna), a blood pressure medicine.

If you need to avoid grapefruit, you should use caution when eating anything made with the seville orange (often used in marmalades), the pomelo (a citrus fruit with a similar flavor to grapefruit but less tart), and limes. These fruits also contain furanocoumarins and may cause the same interactions as grapefruit. Studies with these fruits are not as frequent, so their level of risk is not fully known.

Pomegranate juice (from a berry) is also full of antioxidants and vitamin C. However, this "superfood" has an interaction with the breast cancer treatment ribociclib (Kisqali). The manufacturer recommends that patients avoid pomegranate or grapefruit (and their juices) while taking Kisqali. These juices can increase the blood levels of ribociclib, leading to enhanced side effects such as infections, changes in blood cell counts, weakness, bleeding problems, loss of appetite, nausea and vomiting, diarrhea, hair loss (alopecia), and fatigue.

Increasingly, more drugs are being shown to interact with other juices besides just grapefruit. Aliskiren (Tekturna) is a renin inhibitor medication used to treat high blood pressure. You should avoid drinking orange, apple, or grapefruit juice during treatment with aliskiren, unless your doctor advises otherwise.

Research has shown that drinking orange, apple, or grapefruit juices regularly or within a short period before or after a dose of aliskiren can interfere with the absorption of the medication. Blood levels of the drug may decrease and its blood-pressure lowering effect may be compromised. 

Does Allegra interact with orange juice?

This is one of the most well-known orange juice drug interactions and one of the first ones identified. But it's interaction is a bit different.

Fexofenadine (Allegra Allergy), a popular non-drowsy antihistamine available over-the-counter, can interact not only with grapefruit juice, but also with apple 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 reduced drug transporter mechanism causing less drug to be available in the cell for absorption.

It is recommended that fexofenadine be taken with water and refrain from drinking large amounts of grapefruit, orange, or apple juice

Talk to your healthcare provider

Health care providers should be informed of which medications you take, including any prescription and OTC drugs, herbal supplements and vitamins. Update your pharmacist any time you start or even stop taking a medication. It is important to check for potential drug interactions

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. Do not stop a prescribed medication without talking to your healthcare provider first.

Common drugs that interact with grapefruit

Examples of some of the most common grapefruit or grapefruit juice drug interactions that can occur include:

Other resources

There are numerous other drug interactions with grapefruit and grapefruit juice; this is not a complete list.

Additional grapefruit juice drug interactions, and interactions with other juices or foods, can be researched in the Drug Interaction Checker. You can also check your Patient Medication Guide that accompanies your prescription, and your pharmacist may include a label on your bottle warning you of an interaction.

Always be sure to consult with your doctor or pharmacist to understand the significance of any drug interaction. Follow prescription recommendations for any drug interactions.

Grapefruit juice drug interactions are a popular topic of conversation. You might consider joining the Drugs.com Grapefruit Support group. Here you can chat about this topic at more length, review the latest questions and keep up to date with recent news about interactions.

See also

Sources

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