Pseudoephedrine

(SOO-doh-eff-ed-rin)

What is it? Commonly found in nonprescription cold and allergy medications like Sudafed and Advil Cold & Sinus, pseudoephedrine eases stuffy noses by shrinking swollen blood vessels in your nasal passages, says John Sundy, MD, an asthma and allergy specialist at Duke University Medical Center.

The buzz: Meds with pseudoephedrine were moved behind the pharmacy counter in 2006, and limits were imposed on how much you can buy. Why? The stuff can be used to make methamphetamine, an illegal drug.

You need to know: If you buy a cold or allergy medication and don’t get your usual relief, it may be because the product contains phenylephrine (available over the counter), not pseudoephedrine, Dr. Sundy says. New research shows that some people with stuffy noses get more relief from pseudoephedrine than phenylephrine.

The bottom line: Read labels so you know your phenyl from your pseudo, and ask your pharmacist for a pseudoephedrine product if you think you need it. Know that the drug slightly raises your risk for high blood pressure and might make you jumpy, Dr. Sundy says.

This article was first published in Health magazine, October 2009.