Sinusitis is an inflammation, or swelling, of the tissue lining the sinuses. Normally, sinuses are filled with air, but when sinuses become blocked and filled with fluid, germs (bacteria, viruses, and fungi) can grow and cause an infection.

Conditions that can cause sinus blockage include the common cold, allergic rhinitis (swelling of the lining of the nose), nasal polyps (small growths in the lining of the nose), or a deviated septum (a shift in the nasal cavity).

There are different types of sinusitis, including:

• Acute sinusitis: A sudden onset of cold-like symptoms such as runny, stuffy nose and facial pain that does not go away after 10 to 14 days. Acute sinusitis typically lasts 4 weeks or less.
• Sub-acute sinusitis: An inflammation lasting 4 to 8 weeks.
• Chronic sinusitis: A condition characterized by sinus inflammation symptoms lasting 8 weeks or longer.
• Recurrent sinusitis: Several attacks within a year.