A Dangerous Mix: Learn why it's not safe to take medications with other substances.

• Position: HEADS UP: REAL NEWS ABOUT DRUGS AND YOUR BODY: A Message from Scholastic and the National Institute on Drug Abuse (NIDA

If you take medications and mix them with other medications or substances, they can produce potentially dangerous effects.

YOU PROBABLY ALREADY KNOW anything you ingest can have an effect on your body, whether it's food, liquid, or medication. For instance, you know that if you drink coffee, the caffeine can help you stay awake. And an allergy pill can relieve your stuffy sinuses.

The active ingredients in prescription and over-the-counter (OTC) drugs are tested to make sure they are safe and will have the expected effect. But if you mix those medications with other medications or substances, intentionally or even by accident, they can produce potentially dangerous effects.

Interaction Alert

An active ingredient is the part of a drug that acts on your body. Combining substances can change the way an active ingredient works. This can increase the effect of that ingredient on your body, make it less effective, or have other unexpected results.

For example, prescription medications used to treat attention deficit hyperactivity disorder (ADHD), such as Ritalin, are stimulants. These drugs contain ingredients that increase alertness and attention, but can also increase heart rate and blood pressure. The decongestants in many OTC allergy and cold medications are also stimulants. As a result, taking Ritalin at the same time as a decongestant can cause an additional increase in heart rate and blood pressure. Over time, this can damage the heart.

Even with OTC drugs, you can accidentally exceed the dosage of an active ingredient. For example, think about when you have a cold. You may have a headache and take a pain reliever like Tylenol. Then an hour later you have a cough, so you take cold medicine. But many OTC cold treatments contain acetaminophen, Tylenol's active ingredient. Using these medications together can cause you to exceed the recommended dose of acetaminophen, increasing your risk for liver damage.

Even vitamins, herbal supplements, and foods can interact with medications. For example, the allergy medicine Allegra is less effective if taken with citrus fruit, including grapefruit and oranges. There is also evidence that the herbal supplement St. John's wort can interact with drugs that treat depression, such as Zoloft and Prozac. These interactions can increase the risk of dangerous side effects, including heightened body temperature and seizures.

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