Drug Interactions

What is a drug interaction?

A drug interaction is a change in the effect of a medicine caused by another substance. The effect of the medicine may be changed in different ways.

• The effect of the medicine may be blocked.
• Its effect may be increased.
• Side effects of the medicine may change.

Alcohol and tobacco, as well as prescription and nonprescription drugs, can change the way a medicine works. Vitamins, natural remedies, and certain foods may also interact with medicines.

Sometimes drug interactions are helpful. For example, if you take more than 1 medicine for a medical problem, and one of the medicines increases the effect of other medicines, you may be able to take lower doses. Whenever you take a lower dose of a drug, you lower your chance of side effects.

How does it occur?

There are 2 main types of drug interactions:

• Drug/drug interactions happen when 2 or more medicines react with each other. For example, one drug might make another drug not work as well. Some interactions like this can cause serious problems.
• Drug/food interactions happen when food or drink affects the way a medicine works. For example:
  • Drinking alcohol while taking some medicines, such as sedatives or antidepressants, may make you tired. Or it may slow your reactions. It can even cause you to lose consciousness. You may stop breathing. These effects can make driving a car or operating machinery dangerous.
  • Grapefruit juice affects the way some medicines work. It may also increase the risk of side effects.

Any time you take a new medicine, there is a chance it will interact with other medicines you take. To avoid problems caused by drug interactions, your healthcare provider and pharmacist need to know about all of the medicines, herbal remedies, vitamins, and other supplements you take. This is especially important if you:

• Take several different medicines.
• See more than 1 healthcare provider.
• Buy your medicines at more than 1 pharmacy.
• Have certain health problems, such as heart disease, diabetes, or liver or kidney disease. (These diseases can affect the way your medicines work.)

How can I prevent drug interactions?

• Keep a list of your medicines and dosages with you at all times. Your healthcare providers can then check the list for any possible drug interactions.
• Try to use the same pharmacy for all of your medicines. Nearly every pharmacy uses a computer system to check on the possibility of an interaction of your current medicines with a new prescription. If you are using more than 1 pharmacy and none of the pharmacies has a complete, up-to-date list of your present medicines, you are at risk for possible serious drug interactions.
• Before taking a new medicine, ask your healthcare provider or pharmacist these questions:
  • Can I take it with the other medicines I’m taking?
  • Should I avoid certain foods, beverages, vitamins, or herbs?
  • What are possible signs of a drug interaction?