Q: Why do I sometimes get congested in one nostril? A: Many people don’t realize that every four to six hours, one side of the nose becomes more congested, and the other side decongests. They switch back and forth in a normal cycle. If one side is more obstructed to begin with from a deviated septum or swelling of the soft tissue structures, it will be more noticeable when that side decongests. Here are other reasons for congestion in one nostril: Side sleeping. People also experience stuffiness in the nostril that faces down when they sleep on their side. Deviated septum. If you have blockage that is continuous, it could be a result of a deviated septum. Inflammation and nasal polyps. There are people who have chronic inflammation and nasal polyps. In rare cases, this can be due to a tumor, but these are uncommon. Chronic and persistent obstruction on one side should be evaluated by a doctor, and probably an ENT (otolaryngologist). Foreign objects in the nose. In small children, blockage in one nostril might be due to a foreign body that they put in their nose. If you see thick drainage or pus coming out, it’s time to call your doctor. — ENT-otolaryngologist Michael Benninger, MD Source