Grapefruit and Medication Interactions Overview

The Potential Risks of Mixing Grapefruit with Medications

Grapefruit is high in nutrition and low in calories. It is a good source of nutrients like vitamin C, potassium, and antioxidants, which are beneficial for heart health and the immune system. This citrus fruit is also low in saturated fat, cholesterol, and sodium. Therefore, grapefruit juice and grapefruit can be good additions to a healthy diet.

However, drinking grapefruit juice and eating grapefruit can affect how some medicines work. Grapefruit can increase the amount of some medications in the body, putting you at risk of serious side effects. In addition, grapefruit can make certain medicines less effective by affecting their absorption or transport in the body.

If you’re taking medications that grapefruit juice affects, you should speak to your doctor or pharmacist. Do not stop taking any medication without medical advice.

How Grapefruit Affects Drug Metabolism

Grapefruit products can interact with certain medications. In most cases, the food-drug interaction leads to increased blood levels of the medicine, causing an increased risk of side effects. In some instances, grapefruit products can reduce the blood levels of the medication, making it less effective.

When you take certain drugs by mouth, they are absorbed through transporter cells in the gut. From there, they enter your bloodstream and travel to your liver, where they are metabolized (broken down) or activated by liver enzymes. Grapefruit contains compounds called furanocoumarins that can interfere with liver enzymes and transporter cells, causing blood concentrations of the medicine to fluctuate.

Common Interactions: What Medications Should You Not Eat Grapefruit With?

Some of the common medications with which grapefruit juice and grapefruit interact include:

Cholesterol-lowering medications called statins.
Medications used to treat high blood pressure called calcium channel blockers.
Some antihistamines used to treat allergy symptoms.
Certain anti-anxiety medicines and antidepressants.
Anticoagulants or blood thinners.
Medications used to treat erectile dysfunction.
Corticosteroids used to control inflammation.
Medications used to treat abnormal heart rhythms.
Antiepileptic drugs prescribed to people with seizure disorders.
Certain HIV medications.
Immunosuppressants prescribed to organ transplant patients.

Scientific Concepts Behind Grapefruit-Drug Interactions

Enzyme Inhibition by Furanocoumarin Compounds in Grapefruit

Grapefruit and grapefruit juice can increase the blood levels of certain drugs in the body through enzyme inhibition.

For example, statins are medications that are used to treat high cholesterol. They are broken down by an enzyme called CYP3A4 in the liver and small intestine. Grapefruit juice contains a compound called furanocoumarin that inhibits or blocks the CYP3A4 enzyme. This allows more of the statin drug to stay in the bloodstream longer, increasing the risk of side effects like muscle damage, liver injury, and kidney failure.

Impact on Drug Absorption

Grapefruit juice affects medications in other ways as well, by affecting the absorption and transport of drugs in the body.

An example is fexofenadine (Allegra), an antihistamine used to relieve allergy symptoms that is available by prescription and over the counter. Fexofenadine is transported by certain cells in the small intestine. When you drink grapefruit juice or eat grapefruit, it blocks the action of these transporter cells. This interaction makes less fexofenadine available in the body, causing the medicine to be less effective. Besides grapefruit juice, orange or apple juice can also interact with fexofenadine in this manner.

Variability in Individual Responses

Grapefruit juice affects different people differently. For example, one person may have serious side effects after drinking grapefruit juice while on a statin drug, while another person may not. This is because different people have different amounts of the CYP3A4 enzyme in their intestines and liver; therefore, grapefruit juice can have a variable effect on people taking the same drug at the same dose.

Medications to Avoid with Grapefruit

The U.S. Food and Drug Administration requires some prescription and over-the-counter (OTC) drugs taken by mouth to warn against eating grapefruit or drinking grapefruit juice while on the medication. Some of the categories of drugs that can interact with grapefruit are described below.

Statin Drugs

Some statins like simvastatin (brand name: Zocor), atorvastatin (Lipitor), and lovastatin (Mevacor) have food-drug interactions with grapefruit. These medications are used to lower cholesterol in people with high cholesterol. Consuming grapefruit can affect how statins work. Specifically, grapefruit can increase the blood concentrations of statins, increasing the risk of side effects.

Doctors advise that you should avoid grapefruit and grapefruit juice altogether if you’re taking simvastatin. Drinking an occasional glass of grapefruit juice several hours before or after taking medicine atorvastatin should be safe. However, keep in mind that even with atorvastatin, you should not drink large quantities of grapefruit juice (more than 1.2 liters a day).

You should talk to your doctor or pharmacist about which statin drugs are considered safe with grapefruit products. Grapefruit juice has little to no effect on certain statins, such as fluvastatin (Lescol), pravastatin (Pravachol), rosuvastatin (Crestor), and pitavastatin (Livalo).

Calcium Channel Blockers

Calcium channel blockers are a group of medications used to treat high blood pressure, angina (chest pain), and coronary artery disease. Some calcium channel blockers like nifedipine (Adalat CC, Procardia), felodipine (Plendil), amlodipine (Norvasc), diltiazem (Cardizem, Tiazac), and nisoldipine (Sular) can interact with grapefruit. This can affect how the medicine works, resulting in increased levels of the drug in the blood. Similar to statins, this interaction also increases the risk of side effects.

Anticoagulants and Antiplatelet Drugs

Anticoagulants are blood-thinning medications that prevent blood clots. Warfarin (Coumadin), an inexpensive, commonly prescribed blood thinner, can interact with grapefruit. This interaction increases the effect of warfarin and makes bleeding more likely. The same is true of certain antiplatelet drugs like clopidogrel (Plavix) and ticagrelor (Brilinta).

However, it may be safer to drink fruit juice or eat grapefruit with some of the newer anticoagulants like rivaroxaban (Xarelto), apixaban (Eliquis), edoxaban (Savaysa), and dabigatran (Pradaxa) that do not interact with grapefruit. You do not need to avoid grapefruit if you are on low-dose aspirin or dipyridamole (Persantine).

Erectile Dysfunction Drugs

Men who take erectile dysfunction drugs like sildenafil (Viagra) should know that grapefruit juice can boost blood levels of the drug. While this might be helpful in treating the condition, it can cause side effects like flushing, headache, and low blood pressure.

Antihistamines

Certain medicines may not work properly if you consume grapefruit during treatment, for example, antihistamines like fexofenadine (Allegra).

Antiepileptic Drugs

Grapefruit and grapefruit juice can increase the amount of carbamazepine (Carbatrol, Tegretol), diazepam, and midazolam in the body. These medications are used to treat certain types of seizures in people with epilepsy. Doctors advise avoiding grapefruit and grapefruit juice if you are taking these antiepileptic drugs.

Organ Transplant Rejection Drugs

Immunosuppressants such as cyclosporine (Sandimmune, Neoral), tacrolimus (Prograf), and sirolimus (Rapamune) are drugs that affect the immune system. They are prescribed to people who have undergone organ transplants to prevent organ rejection. Food drug interactions between grapefruit and these immunosuppressant medications can lead to an increase in the blood concentrations of the drugs. If you are on these medications, you should not consume grapefruit without first checking with your doctor.

HIV Medications

Grapefruit juice can increase the blood levels of certain antiretroviral medications such as saquinavir (Invirase) which are used to treat human immunodeficiency virus (HIV). Saquinavir is metabolized (broken down) by the CYP3A4 enzyme, and grapefruit juice blocks this enzyme, making more of the drug available.

Managing and Mitigating Risks

How Do I Find Out If I Can Drink Grapefruit Juice With My Medications?

Family physicians can provide medical advice and trustworthy health information on possible medicine interactions. You should talk to your family doctor about whether grapefruit juice and other fruit juices interact with a particular drug. You can also read the patient information leaflet for information on medicine interactions.

If your doctor tells you not to eat grapefruit or drink grapefruit juice with your medication, check the labels of fruit juices like orange juice to see if they contain tangelos or pomelos (these are a cross between grapefruit and tangerines and can cause some of the same effects). Similarly, Seville oranges (bitter oranges or sour oranges) may also interfere with certain medicines.

Consult Your Healthcare Provider for Alternatives

If grapefruit is a part of your regular diet and your medicines interact with it, your doctor may advise against consuming grapefruit and other juices while taking the medicine. Or they may decide to put you on a different medicine.

For example, while grapefruit can interact strongly with some statin drugs such as simvastatin (Zocor), atorvastatin (Lipitor), lovastatin (Mevacor), it has little to no effect on other statins such as pravastatin (Pravachol), pitavastatin (Livalo), rosuvastatin (Crestor), and fluvastatin (Lescol). If you regularly eat and enjoy grapefruit, your healthcare provider may choose one of the statins that is less affected or does not interact with grapefruit.

Safe Consumption Guidelines for Grapefruit

If you enjoy grapefruit, experts say eating the whole fruit is more beneficial and less risky than drinking grapefruit juice. For one, it takes several grapefruits to make one glass of fruit juice, so eating half a grapefruit is less risky than drinking a glass of grapefruit juice. A single glass of grapefruit juice can lead to a nearly 50% reduction in the liver enzyme that metabolizes certain drugs.

Also, drinking fruit juice delivers higher amounts of sugar and can drive up blood glucose levels. In contrast, eating whole fruit leads to a slower rise in blood sugar. Experts also say eating a whole fruit is more satisfying, filling, and nutritious because you get fiber from the solids.

Frequently Asked Questions

Why Are You Not Supposed To Eat Grapefruit With Cholesterol Medicine?

You should not eat grapefruit with certain cholesterol medicines because doing so can raise the blood levels of the medicines and increase the risk of serious side effects. Grapefruit can block a liver enzyme called CYP3A4, which can lead to higher blood levels of cholesterol medicines called statins. This can increase the risk of side effects such as muscle damage, liver injury, and kidney failure.

How Long After Eating Grapefruit Can I Take Medication?

How long after consuming grapefruit you can take medication depends on the specific medication. For example, doctors advise avoiding grapefruit and grapefruit juice completely if you’re on the cholesterol-lowering drug called simvastatin (Zocor). However, you may drink a small glass of grapefruit juice several hours before or after taking medicine such as atorvastatin (Lipitor), another drug from the same drug class. Grapefruit has little to no effect on certain other statins (pravastatin, rosuvastatin, pitavastatin, fluvastatin). Your doctor or pharmacist can give you more information on interactions between your medicines and grapefruit.

Is Grapefruit A Blood Thinner? Can Grapefruit Cause Bleeding?

Grapefruit is not a blood thinner. However, it can cause some medications that are blood thinners to reach higher blood levels. This can increase the risk of side effects, including bleeding in different parts of the body.

How Does Grapefruit Affect Blood Pressure?

Grapefruit can interfere with the absorption of certain blood pressure medications, leading to either too much or too little of the drug in the bloodstream and causing potentially dangerous fluctuations in blood pressure levels.

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