Grapefruit Juice and medicines may be a deadly combination

Grapefruit Juice and some Medicine May Not Mix and can be DEADLY!!

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Grapefruit juice can be part of a healthful dietmost of the time. It has vitamin C and potassiumsubstances your body needs to work properly.

But it isnt good for you when it affects the way your medicines work.

Grapefruit juice and fresh grapefruit can interfere with the action of some prescription drugs, as well as a few non-prescription drugs.

This interaction can be dangerous, says Shiew Mei Huang, acting director of the Food and Drug Administrations Office of Clinical Pharmacology. With most drugs that interact with grapefruit juice, the juice increases the absorption of the drug into the bloodstream, she says. When there is a higher concentration of a drug, you tend to have more adverse events.

For example, if you drink a lot of grapefruit juice while taking certain statin drugs to lower cholesterol, too much of the drug may stay in your body, increasing your risk for liver damage and muscle breakdown that can lead to kidney failure.

Drinking grapefruit juice several hours before or several hours after you take your medicine may still be dangerous, says Huang, so its best to avoid or limit consuming grapefruit juice or fresh grapefruit when taking certain drugs.

Examples of some types of drugs that grapefruit juice can interact with are:

  • some statin drugs to lower cholesterol, such as Zocor (simvastatin), Lipitor (atorvastatin) and Pravachol (pravastatin)
  • some blood pressure-lowering drugs, such as Nifediac and Afeditab (both nifedipine)
  • some organ transplant rejection drugs, such as Sandimmune and Neoral (both cyclosporine)
  • some anti-anxiety drugs, such as BuSpar (buspirone)
  • some anti-arrhythmia drugs, such as Cordarone and Nexterone (both amiodarone)
  • some antihistamines, such as Allegra (fexofenadine)

Grapefruit juice does not affect all the drugs in the following categories:. Ask your pharmacist or other health care professional to find out if your specific drug is affected.

Too High or Too Low Drug Levels

Many drugs are broken down (metabolized) with the help of a vital enzyme called CYP3A4 in the small intestine. Certain substances in grapefruit juice block the action of CYP3A4, so instead of being metabolized, more of the drug enters the bloodstream and stays in the body longer. The result: potentially dangerous levels of the drug in your body.

The amount of the CYP3A4 enzyme in the intestine varies from one person to another, says Huang. Some people have a lot, and others have just a littleso grapefruit juice may affect people differently when they take the same drug.

While scientists have known for several decades that grapefruit juice can cause a potentially toxic level of certain drugs in the body, Huang says more recent studies have found that the juice has the opposite effect on a few other drugs.

Grapefruit juice reduces the absorption of fexofenadine, says Huang, decreasing the effectiveness of the drug. Fexofenadine (brand name Allegra) is available in both prescription and non-prescription forms to relieve symptoms of seasonal allergies. Fexofenadine may also be less effective if taken with orange or apple juice, so the drug label states do not take with fruit juices.

Why this opposite effect?

It involves the transportation of drugs within the body rather than their metabolism, explains Huang. Proteins in the body known as drug transporters help move a drug into cells for absorption.

Substances in grapefruit juice block the action of a specific group of transporters. As a result, less of the drug is absorbed and it may be ineffective, Huang says.

When a drug sponsor applies to FDA for approval of a drug, the sponsor submits data on how its drug is absorbed, metabolized and transported says Huang. Then we can decide how to label the drug.

FDA has required some prescription drugs to carry labels that warn against consuming grapefruit juice or fresh grapefruit while using the drug, says Huang. And the agencys current research into drug and grapefruit juice interaction may result in label changes for other drugs as well.

Which Other Foods Interact With Medication?

Among the other common foods that affect absorption or effects of medication are:

Black licorice. Many forms of black licorice (used to flavor foods and candy) contain a sweet substance called glycyrrhizin, which can increase the toxicity of certain drugs or worsen side effects.

Drugs it can interact with: University of Maryland warns that if youre taking Lanoxin (a treatment for heart failure and irregular heartbeats), licorice can dangerously raise the risk of toxic side effects. It can also lower the effectiveness of ACE inhibitors and diuretics used to regulate blood pressure, may increase adverse effects from insulin, and boosts the potency of corticosteroids. There have also been reports of women on birth control pills developing high blood pressure and low potassium levels after eating licorice.

Leafy green vegetables. Kale, spinach, Brussels sprouts, and cabbage can make medication that combats blood clots less effective. Thats because these foods are high in vitamin K, a crucial nutrient for clot formation, while the goal of anticoagulant therapy is to slow down production of vitamin K to reduce clot risk. In effect, these foods counteract the drugs desired effect.

Drugs these foods can interact with: Warfarin (Coumadin). If you take this drug, its not necessary to avoid leafy greensinstead doctors advise eating a consistent amount week to week, so your dose of warfarin can be calibrated accordingly.

Milk. Milk and calcium supplements can interfere with absorption of certain infection-fighting drugs, if taken together. The best solution is to wait a few hours after taking these drugs before drinking milk, popping a calcium supplement, or taking antacids (which can also contain calcium).

Drugs it can interact with: Tetracycline and fluoroquinolones (a class of antibiotics that includes Cipro, Levaquin and Avelox).

Alcohol. Mixing alcohol with certain medicationsincluding both prescription and over-the-counter drugscan have a wide range of harmful effects, from nausea and vomiting to drowsiness (increasing risk for car accidents), internal bleeding, liver damage, sudden changes in blood pressure, impaired breathing, and loss of coordination, warns National Institute on Alcohol Abuse and Alcoholism (NIAAA).

Drugs it can interact with: Painkillers, OTC cold, cough, flu and allergy remedies statins, drugs for angina (Isodil), anxiety and epilepsy (Ativan, Klonopin, Xanax,), arthritis (Celebrex, Voltaren), depression (Celexa, Effexor, Lexapro), diabetes (Glucophage, Orinase), enlarged prostate, high blood pressure, infections and other conditions. NIAAA offers a detailed list of drugs that dont mix with alcohol.

Aged, cured or pickled foods. Aged cheeses like cheddar or Swiss, cured meats, and sauerkraut contain tyramine, an amino acid that sparks one of the most feared drug-food interactions when combined with certain antidepressants. The mixture can cause facial flushing, sweating, sudden rise in blood pressure, irregular heartbeats and brain hemorrhage. Tyramine is also found in certain types of wine, such as Chianti, sherry and Riesling.

Drugs it can interact with: Monoamine oxidase inhibitors (MAOI) for depression, and the antibiotics Zyvox and isoniazid.

Chocolate. The caffeine in chocolate (and other caffeinated foods) can trigger severe jitters or tremors when combined with certain meds, and packs a double whammy by irritating the stomach lining, amplifying the side effects of drugs likely to cause nausea. Chocolate also contains some tryamine, the culprit in a food-drug interaction that killed a University of Wisconsin Hospital and Clinics patient.

Drugs it can interact with: MAO inhibitors for depression, some antibiotics, narcotic painkillers like Vicodin and Percoset, asthma medications, and stimulants, such as Ritalin.

Avoiding food-drug interactions

The best ways to protect yourself is to check medication package inserts for interaction warnings and ask your doctor and pharmacist if they advise any dietary restrictions. offers an online interaction checker for both interactions with other drugs and with food.

Tips for Consumers

  • Ask your pharmacist or other health care professional if you can have fresh grapefruit or grapefruit juice while using your medication. If you cant, you may want to ask if you can have other juices with the medicine.
  • Read the Medication Guide or patient information sheet that comes with your prescription medicine to find out if it could interact with grapefruit juice. Some may advise not to take the drug with grapefruit juice. If its OK to have grapefruit juice, there will be no mention of it in the guide or information sheet.
  • Read the Drug Facts label on your non-prescription medicine, which will let you know if you shouldnt have grapefruit or other fruit juices with it.
  • If you must avoid grapefruit juice with your medicine, check the label of bottles of fruit juice or drinks flavored with fruit juice to make sure they dont contain grapefruit juice.
  • Seville oranges (often used to make orange marmalade) and tangelos (a cross between tangerines and grapefruit) affect the same enzyme as grapefruit juice, so avoid these fruits as well if your medicine interacts with grapefruit juice.