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A photo of capsules and tablets.

Too avoid drug interactions, make sure your physician is aware of all the medications, as well as herbal remedies, that you're taking.

Monitoring drug interactions

By Todd D. Sorensen

From eNews, August 30, 2007

The term "drug interaction" is used to describe a situation in which the way a medication would normally act in the body is altered because of another substance. Interactions can occur with food or other drugs, and can adversely affect other medical conditions.

Are they common? Severe drug interactions are not common, but there are risks.

A few years ago, Seldane, a prescription medication for allergies, was pulled from the market, in part, because its interaction with other drugs sometimes resulted in heart problems and patient deaths. Most interactions are much less dangerous and may be so subtle that patients aren't even aware that they're occurring. Food in the stomach, for example, may affect the absorption of a drug into the bloodstream. But it may not cause a person to feel any different.

Occasionally, drugs interact with food in adverse ways. Certain cholesterol medications have been shown to interact with grapefruit juice in ways that cause problems. Affected patients may experience muscle aches, or in more severe cases, there could be a breakdown of muscle tissue.

Sometimes it's not the interaction of two drugs that's problematic; rather, the condition treated by one drug is adversely affected by the other. For example, Sudafed, which is used to treat nasal congestion, can increase your blood pressure. So if you're taking blood pressure medication, Sudafed could counteract its effectiveness. You should be aware that even Sudafed and other over-the-counter medications could interact with prescription drugs.

There are several things you can do to lessen the risk of drug-to-drug interactions. 1) Make sure your physician is aware of all the medications that you're taking. This list should include any prescription and non-prescription drugs, as well as herbal medications. Not everyone considers herbals to be drugs, but studies have shown that they occasionally interact with prescription medications in adverse ways.

2) Use one pharmacy so all your medication records are kept in one place. Pharmacists always review each patient's profile, and pharmacy computer systems alert them to potential interactions. Each pharmacist then uses his or her professional judgment to determine what interactions a patient might encounter. If potential red flags pop up, your pharmacist will consult with your doctor. Solving the problem may be as simple as changing the time of day you take the medication (for example, between meals so it doesn't interact with food), or it may require an alternative prescription medication.

What should you watch for?

If anything seems abnormal, ask your pharmacist or physician about it. The symptoms of drug interactions can run the gamut from general malaise to heart palpitations. There's no particular rule about what you can expect with a drug interaction. But you can ask your pharmacist about the medications you are taking. For example: if something were to occur, what are the potential signs? When is it likely to happen?. The symptoms of drug interactions can be predicted in some cases.

The main thing to remember is that good communication with all your health professionals is key. Patients shouldn't be expected to identify these things themselves, but they should always feel comfortable asking questions.

For more tips on drug interactions, including drug and over-the-counter medications, see the U.S. Food and Drug Administration

Todd D. Sorensen is a professor with the College of Pharmacy at the University of Minnesota.

This column is an educational service of the University of Minnesota. Advice presented should not take the place of an examination by a health-care professional.