Causes of Sinusitis
Mucus helps keep your sinuses clean. Interference with the natural drainage of mucus—caused by colds, allergies, or obstructions—may lead to sinusitis (sinus inflammation and infection). Acute sinusitis comes on suddenly, often right after an upper respiratory infection like a cold. Chronic sinusitis is ongoing swelling of the sinus lining, the result of allergies or chronic infections.
Colds and Other Infections
A cold or flu may cause your sinus and nasal linings to swell. Sinus openings can become blocked, causing mucus to back up. This stagnant mucus then becomes a perfect place for bacteria to grow. Thick, yellow, or discolored mucus is one sign of this infection.
Allergic Reactions
Sensitivity to certain substances causes the release of histamine, which makes your sinus and nasal linings swell. Long-term swelling clogs your sinuses and prevents the cilia from sweeping away mucus. Usually your symptoms are persistent but less severe than with colds.
Obstructions
-
A polyp is a sac of swollen tissue, often the result of an allergy or infection. It may block the middle meatus (the opening where most of your sinuses drain) and even grow large enough to block your nose.
-
A deviated septum is a crooked partition in your nose. Often the result of injury, a deviated septum sometimes blocks your middle meatus.
Date Last Reviewed:
1/15/2007
Date Last Modified:
2/5/2004