Drug-food interactions

Apple Valley, CA
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Common drug-food interactions
IF YOU ARE TAKING	AVOID	EFFECT
Tetracycline	dairy products	decreased absorption
Penicillin, erythromycin	swallowing pills with fruit juice	reduced effects
Blood-thinning medications	foods rich in vitamin K (okra, cabbage) fish oils, large amounts of garlic	reduced effects increased effects
Levodopa (anti-Parkinsonian drug)	diet rich in vitamin B6 (green, leafy vegetables, meat, whole-grain cereals)	reduced effects
MAO inhibitors	broad beans, chicken and beef liver, pickled herring, aged cheeses, Chianti wine	severe headaches, rapid rise in blood pressure (may be fatal)
Diuretics	monosodium glutamate low-potassium diet	facial flushing, chest tightness; potassium deficiency
Digitalis	licorice	sodium retention, reduced effects
Oral contraceptives	diet low in vitamin Be	vitamin Be deficiency
Aspirin, nonsteroidal anti-inflammatory drugs	taking on an empty stomach or with acidic foods	upset stomach
Zivodudine (AZT)	high-fat diet	reduced effects
Tricyclic antidepressants	taking with food	increased absorption
Theophylline	high-protein, low-carbohydrate diet	reduced effects
Lithium	low-salt diet	increased risk of drug toxicity
Dilantin	diet low in folic acid, B vitamins	increased risk of folic acid deficiency
Iron supplements	taking with food, milk, wine, or tea	reduced absorption
Cholestyramine (cholestrol-lowering drug)	diet low in folic acid, vitamins A, D, and K	increased risk of nutritional deficiency

What are drug-food interactions?

Prescription and nonprescription drugs can interact with foods in two different ways. What a person eats can affect the success of a drug regimen, and drug therapy can also alter a person's nutritional status. The extent of specific food-drug interactions varies from person to person depending on age, drug dosage, gender, body size, and overall health. Caffeine and alcohol use also influence the intensity of food-drug interactions. In general, elderly people, children, and the malnourished or chronically ill are most susceptible to problems with certain combinations of diet and medication.

How do drug-food interactions affect the body?

Food usually either interferes with the way a drug is absorbed into the bloodstream or prolongs the time it takes for absorption to occur. Any food in the digestive tract may add to the time required for a medication to reach the walls of the small intestine, where the body absorbs it. Some foods actually prevent the gastrointestinal absorption of certain drugs, particularly antibiotics. To avoid this problem, take medication on an empty stomach. Conversely, if a medication such as aspirin causes stomach irritation, a person will tolerate it better if it is taken with food.

Drugs can also affect a person's appetite. Certain antidepressants and tranquilizers stimulate the appetite. Antibiotics or any medication that produces nausea and vomiting can have an anorexic effect, resulting in appetite loss. Many anticancer drugs have this effect.

Other drugs can interfere with the way the body absorbs certain nutrients. The list ranges from common medications sold over the counter, such as antacids, to oral contraceptives and a variety of prescription drugs taken for specific medical problems.

What can I do myself?
Ask a doctor or pharmacist whether a recommended medication might interact with specific foods or drinks. While taking some medications, a person may have to eliminate certain foods and beverages altogether. With other medications, timing the drug dosage so that food does not interfere with its absorption may be sufficient to avoid interaction.

When should I see my doctor?
A doctor should be consulted before starting any new medication, either prescription or nonprescription. If a prescribed medication interferes with eating or fails to work, a doctor should be consulted immediately.

What will the doctor do?
The doctor will ask about foods and beverages that are normally consumed and the timing of

meals. He or she will then recommend any necessary changes in the diet or the timing of the medication doses to maximize effectiveness of the therapy.

Long-term approach

Always ask a doctor about drug-food interactions whenever a new drug is prescribed. Find out if there are any foods that should be avoided, whether the drug will affect appetite, and whether the drug should be taken with or without food. If a person is on long-term medication for a condition such as arthritis or high blood pressure, he or she should check with a doctor before making any radical dietary changes.

When receiving a drug from a pharmacist, check the label. If no instructions are included relating to drug-food interactions, ask that they be added. People (often the elderly) who must take several different drugs may find it difficult to remember which is which. Clearly labeled packages can remedy this problem.

Advice about drug- food interactions

Many pharmacies are linked to computer networks that supply up-to-date information on potential interactions among drugs and between specific foods and medications. If a person is taking several different medications, a pharmacist can check such a data base to spot potential problems.

This article was last reviewed December 5, 2005 by Dr. James Krider.
Reproduced in part with permission of Home Health Handbook.

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