Taking medications? Learn how some prescription drugs can interact adversely with others (PART 3 of

The effects of prescription medications can be delayed, made stronger, or made weaker when taken with other medications, or with certain foods, beverages, or dietary supplements.

There are many things people can do to take both prescription and over-the-counter medications in a safe manner. One of these is to learn more about interactions. There are three main types: drug interactions with other medications, drug interactions with foods and beverages, and drug interactions with dietary supplements.

This article deals with negative interactions between medications and other drugs.

Most people take at least one prescription medication and close to 40% of people in the U.S. have prescriptions for four or more drugs. When the number of over-the-counter drugs is figured in, there is a potential for adverse reactions to occur. Sometimes a medication that helps with one illness or set of symptoms interacts in a bad way with a medication that is prescribed for something else. Here are some examples:

Antihistamines: Over-the-counter drugs that temporarily relieve a runny nose, or reduce sneezing or an itchy nose, throat, or eyes usually contain antihistamines. Some increase the effects of sedatives or tranquilizers making it difficult to concentrate or to operate a car or machinery. Antihistamines taken with blood pressure medication can cause a person’s blood pressure to increase and may also speed up the heart rate.

Nicotine:  Replacement products, used to quit smoking, can increase the heart rate. People with heart problems or high blood pressure should talk with a health care professional first.

Aspirin: When combined with a prescription blood thinner such as Plavix (clopidogrel), aspirin can cause excessive bleeding.

Antacids: Some over-the-counter drugs used to treat stomach acid can interfere with how antibiotics are absorbed into the bloodstream.

Cholesterol-Lowering Medications: People taking Lipitor (atorvastatin) can encounter side effects when also taking medications used to treat fungal infections.

Beta blockers: Drugs like Toprol XL (metoprolol) and Tenormin (atenolol), used to treat high blood pressure and certain types of heart disease, can worsen the symptoms of asthma and chronic obstructive pulmonary disease (COPD).

Diuretics: These drugs, such as Hydrodiuril (hydrochlorothiazide), can increase blood sugar in people who already have diabetes.

Problems can be avoided. Here are some tips:

  • Ask a doctor or pharmacist what foods and beverages to avoid when taking a medication, a supplement, or an over-the-counter drug.
  • Use one pharmacy or drugstore for all medication needs.
  • Be honest with health care professionals about prescription medications, over-the-counter drugs, and supplements you are currently taking, as well as food preferences.
  • Keep a record of prescription drugs, over-the-counter drugs, dietary supplements and including herbs that are taken. Keep this list handy, especially when doing to medical appointments. A medicine record can be downloaded free at http://www.fda.gov/drugs/resourcesforyou/ucm079489.htm.
  • Read drug labels and pharmacy information carefully.
  • Keep medications in their original containers.
  • Review other articles dealing with drug interactions with dietary supplements and drug interactions with food and beverages.

For more information on using medications safely, please visit U.S. Food & Drug Administration or the Food & Information Center at the USDA Natural Agriculture Library.

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