Chill Pills

High humidity can dampen a medication's effectiveness

SUNDAY, Feb. 29, 2004 (HealthDayNews) -- Do you store your medicines in a bathroom cabinet? If so, it's probably a good idea to choose another location.

Heavy humidity, the kind that fogs up the bathroom mirror when you take a hot shower, can decrease the potency of your pills.

"A medication's potency has to do with its stability -- how long is it going to stay at its maximum strength level -- and extreme humidity can affect that stability," says Frank Ascione, a professor of social and administrative sciences at the University of Michigan's College of Pharmacy.

Ascione says drugs weakened by excess moisture will probably be less effective, but taking them won't harm you. You just might not reap the medication's full benefits.

You can spot when humidity has affected your tablets because they become soft and crumbly. A capsule's gel coating makes it more resilient, but not totally immune, to clammy air.

Ascione recommends you store your medications in a cool, dry area and note the expiration dates stamped on the packages. "Most drugs have a three- to five-year shelf life, so if someone is taking a 30-day supply of medicine, in most cases humidity is not going to make too much difference," he says.

If you're traveling to a humid climate, try to find a cool place to store your pills, but don't panic if you can't, Ascione says.

"If you're going away for a week or a month, the weather conditions probably won't make any difference," he says. "It's only if the medications are going to be sitting in a muggy climate for a year that you have be concerned about humidity and tablet strength."

More information

The American Pharmaceutical Association has compiled this fact sheet about commonly used medications.

SOURCE: Frank Ascione, Pharm.D., Ph.D., professor, social and administrative sciences, and associate dean, academic affairs, College of Pharmacy, University of Michigan
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