Food-Drug Interactions

What happens during a food-drug interaction?

Food-drug interactions can happen with both prescription and over-the-counter (OTC) medications, including antacids, vitamins, iron pills, herbs, supplements, and beverages.

Some nutrients can affect the way you metabolize certain drugs by binding with drug ingredients, thus reducing their absorption or speeding their elimination. For example, the acidity of fruit juice may decrease the effectiveness of antibiotics such as penicillin. Dairy products may blunt the infection-fighting effects of tetracycline. Some green leafy vegetables can cancel out the effects of warfarin, an anticoagulant medication. One kind of antidepressants called MAO inhibitors are dangerous when mixed with foods or drinks that contain tyramine (for instance, beer, red wine, chocolate, processed meat, avocados, and some cheeses). Grapefruit juice can interfere with some blood pressure medications and organ transplant medications by increasing their metabolic breakdown. Some medications are only absorbed if they are taken with a full meal or even a meal high in fat content.

Not all medications are affected by food, but many can be affected by what you eat and when you eat it. Sometimes, taking medications at the same time you eat may interfere with the way your stomach and intestines absorb medication. Other medications are recommended to be taken with food. Be sure to ask your doctor or pharmacist for specific directions on eating prior to or after taking any medication.

What you should remember about food-drug interactions

  • Ask your pharmacist or doctor if there are foods, beverages, vitamins, or supplements you should avoid with your medications.

  • Read the prescription label on the container. If you do not understand something, or think you need more information, ask your doctor or pharmacist.

  • Read directions, warnings, and interaction precautions printed on all medication labels and instructions. Even over-the-counter medications can interact with foods, beverages, or supplements.

  • Take medication with a full glass of water unless told otherwise by your pharmacist or doctor.

  • Do not stir medication into your food or take capsules apart (unless directed by your pharmacist or doctor). This may change the way the drug works.

  • Check with your pharmacist or doctor before taking vitamin pills at the same time you take medication — vitamins and minerals can interact with some drugs.

  • Do not mix medication into hot drinks, because the heat from the drink may destroy the effectiveness of the drug.

  • Never take medication with alcoholic drinks. Alcohol can change medication absorption and may increase or decrease the effectiveness of many medications.

  • Be sure to tell your doctor and pharmacist about all medications you are taking, both prescription and nonprescription.

  • Obtain all your medications from one pharmacy and tell your pharmacist about any OTC, supplements, herbs, or vitamins that you take.

  • Keep all medications in their original containers so they can be easily identified.