Nutrition Column – be Aware of Potential Food and Drug Interactions

Thanks to modern medicine, numerous drugs are available to help treat everything from headaches to high blood pressure to cancer. And although taking medication may not seem like a nutrition-related issue, when food and medication are taken together, they often interact.

Food and drug interactions may make a drug less effective, cause unexpected side effects or increase the action of certain drugs. Some food and drug interactions can even be harmful. Potential effects depend not only on the type of drug, the dosage and the form in which the drug is taken, but also a person’s age, sex, weight, nutritional status and overall health.

To help reduce the risk for potential food and drug interactions, follow dosage directions exactly and practice these general guidelines for taking medications.

– Tell your doctor and pharmacist about all medications that you’re taking, including over-the-counter medications and dietary supplements. Some medications can cause harmful interactions with vitamin and mineral supplements and/or herbal remedies.

– Read all labels on the medication bottles carefully. If you don’t understand the directions, ask your doctor or pharmacist.

– Be sure to take the medication with a full glass of water, if recommended. This is especially important for most cholesterol-lowering medications.

– Pay attention to when the medication should be taken. Some, such as aspirin and ibuprofen, are better taken at mealtime to help avoid stomach irritation. Other medications should be taken on an empty stomach because food may slow their absorption and/or action.

– Check if there are certain types of food and/or beverages that shouldn’t be consumed within several hours of the medication. For example, calcium in milk and milk products decreases the absorption of certain antibiotics, including tetracycline. Most drugs should not be taken with soda or high-acid fruit or vegetable juices. These types of beverages can result in excess stomach acidity, which may cause the drug to dissolve before it reaches the small intestine, thereby decreasing absorption. Also, don’t mix medications with hot beverages. Doing so may alter their effectiveness.

– Tell your pharmacist if you are on a sodium-restricted diet. Some prescription and over-the-counter medications contain sodium, including antacids, headache remedies, laxatives and sedatives.

– Medications should not be taken with alcohol. Alcohol can block the effects of some medications while enhancing the effects of others. Even small amounts of alcohol have been shown to interact with several medications, including antibiotics, allergy remedies, blood thinners and sleeping pills.  

– Don’t disassemble capsules or mix medications in with food. Also, don’t crush or split pills unless instructed to do so by your doctor or pharmacist.

– If you have been taking a specific medication for a long period of time, ask your doctor if there is a potential for any vitamin and/or mineral deficiency and whether a supplement is needed.  

For more information about food and drug interactions as well as a list of specific drug classes and their potential interactions with food, contact your local Cooperative Extension office and request fact sheet 9.361: Nutrient-Drug Interactions and Food, or print it online at

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by Pat Kendall, Ph.D., R.D., Food Science and Human Nutrition Specialist, Colorado State University, Cooperative Extension