Merck Manual

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Some Drug-Food Interactions

Some Drug-Food Interactions

Affected Drug

Interacting Food


Bisphosphonates (such as alendronate, ibandronate, and risedronate)

Any food

Food, even orange juice, coffee, or mineral water, may markedly reduce the absorption and effectiveness of these drugs. Alendronate and risedronate must be taken with plain water at least 30 minutes before the first food, beverage, or drug of the day is taken, and ibandronate must be taken at least 1 hour before.

  • Certain benzodiazepines (such as triazolam)

  • Calcium channel blockers (such as felodipine, nifedipine, and nisoldipine)

  • Cyclosporine

  • Estrogen and oral contraceptives

  • Certain statins (such as atorvastatin, lovastatin, and simvastatin)

Grapefruit juice

Grapefruit juice inhibits enzymes involved in drug metabolism and thereby intensifies the effect of certain drugs, including many that are not listed here.



The fiber in oatmeal and other cereals, when consumed in large amounts, can interfere with the absorption of digoxin.

MAO inhibitors (such as phenelzine and tranylcypromine)

Foods high in tyramine, including many cheeses (such as American processed, cheddar, blue, brie, mozzarella, and Parmesan), yogurt, sour cream, cured meats (such as sausage and salami), liver, dried fish, caviar, avocados, bananas, yeast extracts, raisins, sauerkraut, soy sauce, fava beans, red wine, and certain beers

Severe headache and a potentially fatal increase in blood pressure (hypertensive crisis) can occur if people taking an MAO inhibitor (used most often to treat depression) consume these foods. These foods must be avoided.


Calcium or foods containing calcium, such as milk and other dairy products

These foods can reduce the absorption of tetracycline, which should be taken 1 hour before or 2 hours after eating.

Warfarin (an anticoagulant)

Foods high in vitamin K (such as broccoli, Brussels sprouts, spinach, and kale)

Such foods may reduce the effectiveness of warfarin, increasing the risk of clotting. It is more important that the amount of vitamin K–containing foods consumed daily remain constant than that intake of such foods be limited.

MAO = monoamine oxidase.