Drug Interactions: What You Should Know

Whenever two or more drugs are being taken, there is a chance that there will be an interaction among the drugs. The interaction may increase or decrease the effectiveness of the drugs or the side effects of the drugs. The likelihood of drug interactions increases as the number of drugs being taken increases. Therefore, people who take several drugs are at the greatest risk for interactions. Drug interactions contribute to the cost of healthcare because of the costs of medical care that are required to treat problems caused by changes in effectiveness or side effects. Interactions also can lead to psychological suffering that can be avoided.

There are more opportunities today than ever before to learn about your health and to take better care of yourself. It is also more important than ever to know about the medicines you take. If you take several different medicines, see more than one doctor, or have certain health conditions, you and your doctors need to be aware of all the medicines you take. Doing so will help you to avoid potential problems such as drug interactions.

Drug interactions may make your drug less effective, cause unexpected side effects, or increase the action of a particular drug. Some drug interactions can even be harmful to you. Reading the label every time you use a nonprescription or prescription drug and taking the time to learn about drug interactions may be critical to your health. You can reduce the risk of potentially harmful drug interactions and side effects with a little bit of knowledge and common sense. Drug interactions fall into three broad categories:

• Drug-drug interactions occur when two or more drugs react with each other. This drug-drug interaction may cause you to experience an unexpected side effect. For example, mixing a drug you take to help you sleep (a sedative) and a drug you take for allergies (an antihistamine) can slow your reactions and make driving a car or operating machinery dangerous.
• Drug-food/beverage interactions result from drugs reacting with foods or beverages. For example, mixing alcohol with some drugs may cause you to feel tired or slow your reactions.
• Drug-condition interactions may occur when an existing medical condition makes certain drugs potentially harmful. For example, if you have high blood pressure you could experience an unwanted reaction if you take a nasal decongestant.

Drug Interactions and Over-the-Counter Medicines

Over-the-counter (OTC) drug labels contain information about ingredients, uses, warnings and directions that is important to read and understand. The label also includes important information about possible drug interactions. Further, drug labels may change as new information becomes known. That's why it's especially important to read the label every time you use a drug.

• The "Active Ingredients" and "Purpose" sections list:
  • the name and amount of each active ingredient
  • the purpose of each active ingredient

• The "Uses" section of the label:
  • tells you what the drug is used for
  • helps you find the best drug for your specific symptoms

• The "Warnings" section of the label provides important drug interaction and precaution information such as
  • when to talk to a doctor or pharmacist before use
  • the medical conditions that may make the drug less effective or not safe
  • under what circumstances the drug should not be used
  • when to stop taking the drug

• The "Directions" section of the label tells you:
  • the length of time and the amount of the product that you may safely use
  • any special instructions on how to use the product

• The "Other Information" section of the label tells you:
  • required information about certain ingredients, such as sodium content, for people with dietary restrictions or allergies

• The "Inactive Ingredients" section of the label tells you:
  • the name of each inactive ingredient (such as colorings, binders, etc.)

• The "Questions?" or "Questions or Comments?" section of the label (if included):
  • provides telephone numbers of a source to answer questions about the product

Learning More About Drug Interactions

Talk to your doctor or pharmacist about the drugs you take. When your doctor prescribes a new drug, discuss all OTC and prescription drugs, dietary supplements, vitamins, botanicals, minerals and herbals you take, as well as the foods you eat. Ask your pharmacist for the package insert for each prescription drug you take. The package insert provides more information about potential drug interactions.

Before taking a drug, ask your doctor or pharmacist the following questions:

• Can I take it with other drugs?
• Should I avoid certain foods, beverages or other products?
• What are possible drug interaction signs I should know about?
• How will the drug work in my body?
• Is there more information available about the drug or my condition (on the Internet or in
• health and medical literature)?

Know how to take drugs safely and responsibly. Remember, the drug label will tell you:

• what the drug is used for
• how to take the drug
• how to reduce the risk of drug interactions and unwanted side effects

If you still have questions after reading the drug product label, ask your doctor or pharmacist for more information

This information is brought to you by the Council on Family Health in cooperation with the National Consumers League and the U.S. Food and Drug Administration.