A runny or stuffy nose can be due to colds, allergies, sinus infections or the flu. When there is an excess of mucus secretions the nose is runny. The additional secretions drain from the front of the nose, or down the back (post-nasal drip). The sensation of a stuffy nose occurs when the membranes that line the nose become swollen from inflamed blood vessels.
Update Date 8/12/2011
Updated by: Linda Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.