Drug Interactions

What is a drug interaction?

A drug interaction is a change in the effect of a drug caused by some other substance. The effect of the drug may be blocked or increased, or the side effects may change. Alcohol and tobacco, as well as prescription and nonprescription medicines, can change the way a drug works. Vitamins, natural remedies, and certain foods may also interact with drugs.

There are many different types of drug interactions. 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 of some of your medicines. Whenever you take a lower dose of a drug, you lower your chance of side effects from that drug.

How does it occur?

Drug interactions fall into 2 broad categories:

• Drug/drug interactions happen when 2 or more drugs react with each other. For example, one drug might make another drug not work as well. Some drug interactions can cause serious problems.
• Drug/food interactions happen when food or drinks affect the way a drug works. For example, drinking alcohol while taking some drugs, such as sedatives or antidepressants, may make you tired, or it may slow your reactions. It can even cause you to fall unconscious and stop breathing. These effects can make driving a car or operating machinery dangerous.
  

  Grapefruit juice is an example of a food that 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 possibility it will interact with other medicines you take. To avoid problems caused by drug interactions, your healthcare provider and pharmacist need to be aware of all the medicines, herbal remedies, vitamins, and other supplements that you take. This is especially important if you:

• take several different medicines
• see more than one healthcare provider
• buy your medicines at more than 1 pharmacy
• have certain health problems, such as heart disease, diabetes, or liver or kidney disease, because these diseases can affect the way your medicines work.

What can I do to 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 and up-to-date list of your present medicines, serious drug interactions could occur.
• 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?

Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.

HIA File drug4263.htm Release 13/2010