What Is Sinus Infection (Sinusitis)?

Symptoms of sinus infection include pain in the forehead or between the eyes, toothache, feeling of fullness in the mid-face, stuffy nose, and congestion.

The sinuses contain defenses against foreign viruses and bacteria (germs). If the normal defenses are disrupted, they may allow bacteria normally present in the nasal passages to enter any of the sinuses. Once there, the bacteria may stick to the lining cells and cause a sinus infection.

Acute sinusitis usually lasts less than eight weeks or occurs no more than three times per year with each episode lasting no longer than 10 days. Medications are usually effective against acute sinusitis. Successful treatment counteracts damage done to the mucous lining of the sinuses and surrounding bone of the skull.

Chronic sinusitis lasts longer than eight weeks or occurs more than four times per year with symptoms usually lasting more than 20 days.

The sinuses are covered with a mucus layer and cells that contain little hairs on their surfaces (cilia). These help trap and propel bacteria and pollutants outward.