National Consumers League


NCL Health Issues

What are drug interactions?

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When one drug interacts or interferes with another, this changes the way one or both of the drugs work in the body and can cause unexpected, and sometimes dangerous, side effects.


In order to prevent drug interactions with an over-the-counter (OTC) medicine, you should make sure your health care professional knows what prescriptions, dietary supplements, and other OTC drugs you’re already taking, and ask whether it’s safe to combine them.

OTC medicines are required to carry the Drug Facts label so you can easily find the “active ingredients,” as well as the indications and directions for taking each medicine correctly. The Drug Facts label is there for a reason: so you will have the facts to select the most appropriate OTC products and to understand each drug’s risks and benefits.

Look for the section called active ingredient, which is where the actual medicines are listed. For prescription drugs, talk to your doctor or pharmacist, since many prescription pain medications also contain one of the four common pain relievers: aspirin, acetaminophen, ibuprofen, or naproxen sodium.

Although OTC products are safe when taken according to the directions on their labels they are still powerful medicines that must be taken with care. It is also important to know that many common prescription pain medicines also contain the same ingredients used in OTC pain and cough/cold products. This makes it even more important that you know what’s in the medicines you take, and how to take them correctly.