Grapefruit is one of the well-loved citrus fruits for many reasons; besides the juiciness and refreshing taste, this fruit is a great fiber source and is also packed with vitamin C. Not only the fruit grapefruit juice is also very popular. There is no doubt about the health benefits of grapefruit and grapefruit juice.
However, you often hear about the effects of grapefruit on the medications. You may have heard about the impact of grapefruit juice on medicine from friends or family members, or you may have come across this information on your news feed or television commercials, which makes you wonder if your medications are affected by this citrus fruit. This article will highlight the key facts regarding how grapefruits affect certain medications and valuable tips to safely enjoy your favorite fruit while avoiding unwanted side effects.
How does grapefruit juice affect certain medications?
Your doctor may have warned you about specific drug interactions between two or more medications that you're taking. A similar concept applies to food and drugs. Drug-food interaction can happen between particular food or supplements and medications; these interactions can increase the drug's blood levels, leading to increased side effects, or they can make the drug less effective, which can worsen the health condition being treated. In addition to prescription medications, keep in mind that over-the-counter (OTC) drug products and supplements can also be affected by grapefruit and its products.
When you take a medication by mouth, it is absorbed into the bloodstream. Then it travels to the liver, where it is metabolized or broken down by certain liver enzymes. As a matter of fact, the liver is considered the primary site for drug metabolism, and many drugs must pass through the liver. The liver breaks down medication via a group of enzymes called cytochrome P-450. Grapefruit and its products can affect the levels of many medications because it inhibits the CYP3A4 enzyme of the cytochrome P450 system. Many drugs are metabolized by CYP3A4; therefore, by blocking the activity of this enzyme, grapefruit juice increases the drug levels in the body. This is not one of the scenarios where it's "the more, the merrier." In fact, increased drug levels can lead to increased side effects and toxicity, even putting a person at higher risk for liver or kidney injury.
One thing to remember is that, due to genetics, different people have different amounts of CYP3A4 in their intestines and liver. Therefore, the effects of grapefruit juice on the same drug may vary from person to person.
What are the effects of grapefruit juice on medications?
As mentioned, drug interactions among certain medications can either cause an increase in drug levels leading to undesirable side effects, or it can cause certain medications to be less effective due to a low level of drug in the body.
This mechanism is similar to grapefruit juice and certain medications. When you take medication broken down by CYP3A4, the presence of grapefruit juice can block the action of this enzyme, in turn, more drugs in the bloodstream for a more extended period. The result is increased side effects and toxicity. Statin, the popular medication used to treat high cholesterol, is an example of this interaction. You may experience side effects such as muscle pain, nausea, vomiting, and diarrhea when you drink grapefruit juice while taking certain statin medications.
While certain medications’ levels are increased by grapefruit juice, this citrus fruit can have the opposite effect on others. Grapefruit juice also affects specific proteins that transport the drug into the cells. Fexofenadine (Allegra) is a second-generation antihistamine used to relieve the symptoms of seasonal allergies. The drug transporters facilitate the movement of fexofenadine into the cells for absorption. By blocking the action of these transporter cells, less fexofenadine enters the blood, leading to less effective therapy. Specifically for fexofenadine (Allegra), other juices, such as orange and apple juice, can also make this medicine less effective. Therefore, fexofenadine should not be taken with any fruit juice. The time it takes for the drug to be cleared from the body varies from person to person. You should talk to your doctor to see how long you must wait between taking fexofenadine and consuming fruit juice.
Which medications are affected by grapefruit and grapefruit products?
“Statins” are a group of medicines used to lower LDL. This “bad” cholesterol can reduce the risk of heart disease, heart attack, and stroke. Examples of agents from this drug class include atorvastatin (Lipitor), simvastatin (Zocor), and rosuvastatin (Crestor).
As mentioned above, one common fact about these cholesterol-lowering medications is that they can be affected by grapefruit juice. More specifically, grapefruit and grapefruit juice can increase the blood levels of statins. In some cases, high blood levels of statins can be dangerous. Let your doctor know if you start to experience unusual muscle pain, as it can be a sign of rhabdomyolysis (muscle breakdown).
Besides statins, below are some of the medications that can interact with grapefruit products. More specifically, grapefruit and grapefruit products can increase blood levels of these medications.
● Medications for arrhythmia or irregular heartbeats: amiodarone (Cordarone), dronedarone (Multaq);
● Anti-anxiety medicines: buspirone (Buspar), benzodiazepines such as diazepam (Valium), midazolam (Versed), triazolam (Halcion);
● Antimicrobials: erythromycin, rilpivirine (and other rilpivirine-containing HIV medications), primaquine, albendazole, women only -- itraconazole (Sporanox)
● Blood thinners: apixaban (Eliquis), rivaroxaban (Xarelto), ticagrelor (Brilinta), clopidogrel (Plavix);
● Mental health medications and central nervous system (CNS) agents: sertraline (Zoloft), carbamazepine, ziprasidone (Geodon), quetiapine (Seroquel), fluvoxamine (Luvox), lurasidone (Latuda), bupropion (Wellbutrin);
● Opioid pain medicines: oxycodone, methadone;
● Antihistamines: fexofenadine (Allegra);
● Blood pressure medicines: felodipine, nimodipine, nicardipine;
● Cytotoxic agent/cancer medications: cyclophosphamide, imatinib;
● Immunosuppressants: cyclosporine, tacrolimus, sirolimus;
● Erectile dysfunction medicine: sildenafil (Viagra), tadalafil (Cialis);
● Corticosteroids: budesonide (Entocort EC), methylprednisolone (Medrol);
● Birth-control: estrogen-containing products such as Loestrin, Yasmin;
This is not a complete list of medications that can be affected by grapefruit products. Talk to your doctor or pharmacist if you have questions about the interactions between grapefruit and other medicines including prescription, over-the-counter (OTC) medications, and supplements.
One commonly asked question is whether or not grapefruit should be avoided entirely. There is no straightforward answer to this question. The reason is that grapefruit and grapefruit juice may affect each person differently, depending on the type of medications, medication dosing, genetics, metabolism, and how much grapefruit product is consumed. Another thing to keep in mind is that other citrus fruits such as oranges and pomelos can also interact with medications.
A few key things to remember is that it does not take much for an interaction to take place; one glass of grapefruit juice or one whole grapefruit is enough to cause a spike in drug levels. Depending on a person’s health history and metabolism, grapefruit products can interact with medication for up to 3 days.
The good thing is that if you are taking a medication that can be affected by grapefruit juice, there may be another agent in the same drug class that is not affected by this citrus fruit, or the effect is a lot less significant. Talk to your doctor if grapefruit is a staple of your diet.
This same concept is also true with statins. In other words, grapefruit products do not have the same effects on all statins. Atorvastatin (Lipitor), lovastatin (Mevacor), and simvastatin (Zocor) are affected by grapefruit products the most. On the other hand, rosuvastatin (Crestor), pitavastatin (Livalo), and pravastatin (Lescol XL) aren’t affected as much by grapefruit products.
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