By Mark Cichocki, R.N., About.com
Updated: October 11, 2007
About.com Health's Disease and Condition content is reviewed by the Medical Review Board
Are your symptoms merely irritating, or could they be a sign of allergies? More >
The best way to treat a headache is to prevent it. Learn how. More >
©2009 About.com, a part of The New York Times Company.
All rights reserved.