An allergy is an immune response to a foreign substance, or an allergen. While usually harmless, environmental allergens, such as dust, mold, and pet or animal dander, may often cause a stuffy nose, itchy nose and throat, mucus or cough.
An allergy is an immune response to a foreign substance, or an allergen. While usually harmless, environmental allergens, such as dust, mold, and pet or animal dander, may often cause a stuffy nose, itchy nose and throat, mucus or cough.