5 reasons this can happen
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: