Food and Drug Interactions in Coffee

Food and drug interactions found in coffee

Food/Drug Interactions in Coffee
Allopurinol: Coffee and other beverages containing methylxanthine stimulants (caffeine, theophylline, and theobromine) reduce the effectiveness of the antigout drug allopurinol, which is designed to inhibit xanthines.

Analgesics: Caffeine strengthens over-the-counter painkillers (acetaminophen, aspirin, and other nonsteroidal antiinflammatories [NSAIDS] such as ibuprofen and naproxen). But it also makes it more likely that NSAIDS will irritate your stomach lining.

Antibiotics: Coffee increases stomach acidity, which reduces the rate at which ampicillin, erythromycin, griseofulvin, penicillin, and tetracyclines are absorbed when they are taken by mouth. (There is no effect when the drugs are administered by injection.)

Antiulcer medication: Coffee increases stomach acidity and reduces the effectiveness of normal doses of cimetidine and other antiulcer medication.

False-positive test for pheochromocytoma. Pheochromocytoma, a tumor of the adrenal glands, secretes adrenalin, which is converted to VMA (vanillylmandelic acid) by the body and excreted in the urine. Until recently, the test for this tumor measured the levels of VMA in the patient's urine and coffee, which contains VMA, was eliminated from patients' diets lest it elevate the level of VMA in the urine, producing a false-positive test result. Today, more finely drawn tests make this unnecessary.

Iron supplements: Caffeine binds with iron to form insoluble compounds your body cannot absorb. Ideally, iron supplements and coffee should be taken at least two hours apart.

Birth control pills: Using oral contraceptives appears to double the time it takes to eliminate caffeine from the body. Instead of five to six hours, the stimulation of one cup of coffee may last as long as 12 hours.


Monoamine oxidase (MAO) inhibitors: Monoamine oxidase (MAO) inhibitors are drugs used to treat depression. They inactivate naturally occurring enzymes in your body that metabolize tyramine, a substance found in many fermented or aged foods. Tyramine constricts blood vessels and increases blood pressure. Caffeine is a substance similar to tyramine. If you consume excessive amounts of a caffeinated beverage such as coffee while you are taking an MAO inhibitor, the result may be a hypertensive crisis.

Nonprescription drugs containing caffeine: The caffeine in coffee may add to the stimulant effects of the caffeine in over-the-counter cold remedies, diuretics, pain relievers, stimulants, and weight-control products containing caffeine. Some cold pills contain 30 mg caffeine, some pain relievers 130 mg, and some weight-control products as much as 280 mg caffeine. There are 110150 mg caffeine in a five-ounce cup of drip-brewed coffee.

Sedatives: The caffeine in coffee may counteract the drowsiness caused by sedative drugs; this may be a boon to people who get sleepy when they take antihistamines. Coffee will not, however, "sober up" people who are experiencing the inebriating effects of alcoholic beverages.

Theophylline: Caffeine relaxes the smooth muscle of the bronchi and may intensify the effects (and/or increase the risk of side effects) of this antiasthmatic drug.

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