Sinusitis Health Channel

Definition

Sinusitis refers to inflammation of the sinuses. This is generally caused by a viral, bacterial, or fungal infection.

The sinuses are air-filled spaces in the skull (behind the forehead, cheeks, and eyes) that are lined with mucous membranes. Healthy sinuses are sterile (meaning that they contain no bacteria or other organisms) and open, allowing mucus to drain and air to circulate.

When inflamed, the sinuses become blocked with mucus and can become infected. Each year, over 30 million adults and children get sinusitis.

Sinusitis can be acute (lasting anywhere from 2 - 8 weeks) or chronic, with symptoms lingering much longer.

See also: Chronic sinusitis

Alternative Names

Acute sinusitis; Sinus infection; Sinusitis - acute

Causes, incidence, and risk factors

Sinusitis can occur from one of these conditions:

• The small openings (ostia) from the sinuses to the nose become blocked.
• Small hairs (cilia) in the sinuses, which help move mucus out, are not working properly.
• Too much mucus is produced.

When the sinus openings become blocked and mucus accumulates, this becomes a great breeding ground for bacteria and other organisms.

Sinusitis usually follows respiratory infections, such as colds, or an allergic reaction. Some people never get sinusitis, and others develop sinusitis frequently.

People more likely to get frequent sinusitis include those with cystic fibrosis and those with immune systems weakened by HIV or chemotherapy.

The following may increase your risk for developing sinusitis:

• Air pollution and smoke
• Asthma
• Changes in altitude (flying or scuba diving)
• Dental work
• Deviated nasal septum, nasal bone spur, or polyp
• Foreign body in your nose
• Frequent swimming or diving
• Gastroesophageal reflux disease (GERD)
• Hospitalization, especially if you are in the hospital because of a head injury or have had a tube placed into your nose (nasogastric tube)
• Overuse of nasal decongestants (rather than continuing to relieve congestion, the problem gets worse when these are used too often or for too long)
• Pregnancy

Cystic fibrosis is one of a number of diseases that prevent the cilia from working properly.