http://www.healthcentral.com/allergy/guide-153947-75.html    Hi Mary,   Runny nose may be caused by allergy or other triggers. If you have a dog, cat or other pet runny nose may be triggered by being allergic to them. Many more questions need to be answered in order to make the correct diagnosis. A physical exam looking for other signs of allergy would also be helpful.   Some people may have runny nose after head trauma or sinus surgery. Some non-allergic triggers include fragrances, indoor and outdoor pollution, tobacco smoke and paint fumes. Some people have runny nose associated with stress, emotional upset and excitement.   Of course allergy is a common cause of runny nose. Here is a link to more information about allergic rhinitis and treatment: Allergic Rhinitis   See your doctor in order to establish your diagnosis. The common cold should only cause runny nose and other nasal symptoms for 5-7 days.   Good Luck,   J. Thompson, MD.