By nature and definition, drugs are powerful chemicals that can alter certain body functions. No drugs - whether obtained by prescription or over-the-counter - should be taken lightly.

And one important consideration is what else you might take into your body while the drugs are working. Physicians and pharmacists recognize that some foods and drugs, when taken during the same period of time, can alter the body's ability to utilize a particular food or drug or cause serious side effects.On the other hand, some drugs are better taken with food, because the food can buffer the effects of the drugs.

The information on this page is provided by the National Consumers League in connection with the American Pharmaceutical Association, the Food and Drug Administration and the Food Marketing Institute. It is not designed to be used in place of advice from a family physician or family pharmacist but to help acquaint consumers with possible food and drug interactions.

Any time your doctor prescribes drugs, advises the league, make sure he knows about every other drug you are taking, including those you obtain without a prescription. If you have any problems related to medication, call your physician or pharmacist immediately. One drug may interact with another, in some cases creating serious medical problems.

Food and drug interactions will also vary according to the dosage, your age, sex and overall health.

Although alcohol is actually a drug rather than a food, its interaction with drugs is covered here because, when consumed while taking certain medications, it can be extremely dangerous. Cigarettes can also diminish the effectiveness of medications or create added hazards with certain medication. Caffeine, too, can affect the action of some drugs.

Medications should never be taken during pregnancy without the advice of your physician.

(Additional information)

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Learn how your medicine reacts with food and drink

ANTICOAGULANTS: Reduce clotting of the blood.

Moderation in consumption of foods high in vitamin K is recommended because vitamin K produces blood-clotting substances. (Such foods include spinach, cauliflower, brussel sprouts, potatoes, vegetable oil and egg yolk.)

ANTIHISTAMINES: Used to relieve or prevent the symptoms of colds and hay fever and other types of allergy. They act to limit or block histamine, which is released by the body when it is exposed to substances that cause allergic reactions.

Avoid taking with alcoholic beverages; the alcohol increases drowsiness and slowed reactions.

ANTI-HYPERTENSIVES: Relax blood vessels, increase the supply of blood and oxygen to the heart, regulate heart beat and lessen its work load.

Use of sodium should be restricted.

ASPIRIN: Reduces pain, fever and inflammation.

To avoid stomach upset, take with food. Do not take with fruit juice or alcohol.

BRONCHODILATORS: Used to treat symptoms of bronchial asthma, chronic bronchitis and emphysema.

Avoid eating or drinking large amounts of foods or beverages that contain caffeine, because both bronchodilators and caffeine stimulate the central nervous system.

CODEINE: A narcotic that is contained in many cough and pain relief medications.

Do not drink alcohol, which can increase sedative effect. Take with meals, snacks or milk because of possible stomach upset.

CORTICOSTEROIDS: Provide relief to inflamed areas of the body. They lessen swelling, redness, itching and allergic reactions.

Avoid alcohol and foods high in sodium. Take with foods to prevent stomach upset.

DIURETICS: Increase the elimination of water, sodium and chloride from the body.

Loss of potassium, calcium and magnesium occurs with some diuretics. Consult with your doctor or pharmacist about possible supplements.

ERYTHROMYCIN: An antibiotic used to treat a wide variety of infections, including those of the throat, ears and skin.

These drugs vary in their reactions with food; consult your doctor or pharmacist for instruction.

IBUPROFEN: Relives pain and reduces inflammation and fever.

Take with food or milk to lessen stomach irritation. Avoid taking with foods or alcoholic beverages that tend to bother your stomach.

INDOMETHACIN: Used to treat the painful symptoms of certain types of arthritis and gout.

Take with food to lessen stomach irritation. Avoid taking with foods or alcoholic beverages that bother your stomach.

LAXATIVES: Some stimulate the action of the muscles lining the large intestine. Others soften the stool or add bulk or fluid to help food pass through the system.

Excessive use of laxatives can cause loss of essential vitamins and minerals and may require replenishment of potassium, sodium and other nutrients through the diet. Mineral oil can cause poor absorption of some vitamins. Discuss use of laxatives with your doctor or pharmacist.

LITHIUM CARBONATE: Regulates changes in hormone levels in the brain, balancing excitement and depression.

Follow the dietary and fluid intake instructions of your physician to avoid serious toxic reactions.

MAO INHIBITORS: Used primarily to treat depression.

A potentially fatal interaction can occur with foods containing tramine, a chemical in alcoholic beverages, particularly wine, and in many foods such as hard cheeses, chocolate, beef or chicken livers. Be sure to follow physician's instructions.

METHENAMINE: Used to treat urinary tract infections.

Cranberries, plums, prunes and their juices help the action of this drug. Avoid citrus fruits and juices. Eat foods with protein, but avoid dairy products.

METRONIDAZOLE: An anti-infective that is used to treat intestinal and genital infections due to bacteria and parasites.

Avoid alcohol, which may cause stomach pain, nausea, vomiting, headache and flushing.

NARCOTIC ANALGESICS: Used for relief of pain. Examples include meperidine, morphine, oxycodone, pentazocine and propoxyphene.

Do not drink alcohol because of sedative effect. Take with food to avoid stomach upset.

PENICILLINS: Antibiotics used to treat a wide variety of infections.

Amoxicillin and bacampicillin may be taken with food; however, absorption of other penicillins is reduced when taken with food.

PIROXICAM: Used to treat pain, inflammation and other symptoms caused by certain types of arthritis.

Take with a light snack to avoid stomach irritation. Avoid alcohol.

SLEEP MEDICATIONS: Used as sedatives to promote drowsiness.

Avoid alcohol.

SULFA DRUGS: Anti-infectives that are used to treat stomach and urinary infections.

Avoid alcohol, which may cause nausea.

TETRACYCLINES: Antibiotics that are used to treat a wide variety of infections.

Should not be taken within two hours of eating dairy products such as milk, yogurt or cheese, or taking calcium or iron supplements.

ULCER MEDICATIONS: Drugs such as cimetidine, famotidine and ranitidine work to reduce the amount of acid in the stomach.

Follow the diet your doctor orders.

VASODILATORS: Used to relax veins and arteries to reduce work of the heart.

Use of sodium should be restricted.