The most common causes of nasal congestion are the following:
- Viral upper respiratory infections (Common Cold)
- Allergies
Nasal and sinus congestion is the result of swollen or dilated blood vessels in the membranes of the nose and air passageways. These membranes have an extraordinary ability to expand, and have a plentiful supply of blood vessels. As the membranes start to swell and expand, you start to feel congested.