Causes - Sinus Infection

Sinusitis typically follows an upper respiratory infection (for example, the common cold) or an allergic reaction (like hay fever, also called allergic rhinitis). These can cause inflammation and swelling that prevents the sinuses from draining properly. This makes the sinuses a great place for organisms like bacteria, viruses, and fungus to live and grow rapidly.

Other common causes for sinusitis include the following:

Allergies (hay fever, tobacco smoke, dry air, pollutants)

Changes in atmospheric pressure (for example, from swimming or climbing high altitudes)

Infections from dental problems

Disease or an abnormal structure in the sinus area (such as nasal polyps, deviated septum, or nasal bone spur)

Physical injury to the sinuses

Bacteria, viruses, and fungi

Poorly treated recurrent cases of sinusitis can cause chronic sinusitis