Budesonide (Nasonex) Is Used To Prevent And Treat Seasonal And Year-Round Allergy Symptoms (Such As Stuffy/Runny Nose, Itchy Eyes/Nose/Throat, Sneezing). Budesonide Belongs To A Class Of Drugs Known As Corticosteroids. It Works By Reducing Swelling (Inflammation) In The Nasal Passages.