Nasal congestion can be caused by anything that irritates or inflames the nasal tissues. Infections — such as colds, flu or sinusitis — and allergies are frequent causes of nasal congestion and runny nose. Sometimes a congested and runny nose can be caused by irritants such as tobacco smoke and car exhaust. This condition is called nonallergic rhinitis or vasomotor rhinitis.
Less commonly, nasal congestion can be caused by a tumor.
Causes shown here are commonly associated with this symptom. Work with your doctor or other health care professional for an accurate diagnosis.