Nasal polyps are small, sac-like growths made up of inflamed tissue lining the nose. They often occur in groups, like grapes on a stem. Small nasal polyps may cause few problems, but larger ones can affect your breathing, lead to sinus infections and diminish your sense of smell. Nasal polyps typically develop in the mucous lining of the nose, but they can also develop in one or more of your sinuses. Treatment for nasal polyps depends on many factors, so make sure you discuss all of your options with your doctor.