What is a drug interaction?

Sometimes researchers discover that certain drugs, foods, or vitamin or herbal supplements affect one another and can make a medication less, or more, powerful than was intended or lead to other side effects. Other times a patient may neglect to divulge all medications that he or she is taking and unintentionally set up a situation for altered effectiveness or side effects. Both cases describe interactions - when substances behave differently in combination from how they would on their own.

A drug interaction is a change in the effect of a drug when taken with a certain other drug, a supplement or food. Its effect may increase or decrease, or a side effect may occur.

Drug interactions occur via various mechanisms. Here are some common scenarios:

• Drug X increases the absorption of drug Y.
• Drug X decreases the absorption of drug Y.
• Drug X increases the elimination of drug Y from the body.
• Drug X reduces the elimination of drug Y from the body.
• Drug X prevents drug Y from binding to an important enzyme needed for drug Y to function.
• Drug X and drug Y have similar effects. Combining both drugs leads to undesirable results.
• Sometimes drug X and drug Y may have opposite effects. Combining both drugs reduces their expected benefit.  

Regardless of the mechanism, it is important to recognize the drug interaction as soon possible in order to prevent treatment failure or complications. To avoid drug interactions, always let your care providers know which drugs you are taking or stopping 

Drug interactions occur via various mechanisms. Here are some common scenarios:

• Drug X increases the absorption of drug Y.
• Drug X decreases the absorption of drug Y.
• Drug X increases the elimination of drug Y from the body.
• Drug X reduces the elimination of drug Y from the body.
• Drug X prevents drug Y from binding to an important enzyme needed for drug Y to function.
• Drug X and drug Y have similar effects. Combining both drugs leads to undesirable results.
• Sometimes drug X and drug Y may have opposite effects. Combining both drugs reduces their expected benefit.  

Regardless of the mechanism, it is important to recognize the drug interaction as soon possible in order to prevent treatment failure or complications. To avoid drug interactions, always let your care providers know which drugs you are taking or stopping.