Conditions InDepth: Sinusitis

The sinuses are hollow areas in the skull that are arranged in pairs. Sinusitis occurs when the tissue lining the sinuses in the skull around the nose (the paranasal sinuses) becomes inflamed and infected. Acute sinusitis usually lasts about 1-4 weeks, while chronic sinusitis is diagnosed when symptoms last three or more months. The third form, recurrent acute sinusitis, occurs more than three times a year.

Paranasal Sinuses

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Although sinusitis may begin during or after a viral infection, the condition itself is usually due to a bacterial infection or allergic conditions.

Acute infectious sinusitis may be caused by any number of bacteria, including:

  • Hemophilus influenzae
  • Streptococcus pneumoniae
  • Moraxella catarrhalis
  • Staphylococcus aureus
  • Streptococcus pyogenes

These are all bacteria that are often found in the nose and throat of healthy people and which cause other common conditions, such as bronchitis and ear infections .

Certain other bacteria and fungi, such as Aspergillus , can be a cause of chronic sinusitis.

Sinus Infection

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There are three main factors that predispose a person to developing sinusitis:

  • Blockage of the small openings that run between the sinuses and the nose
  • Malfunction of the tiny hairs (cilia) that are responsible for moving mucus and organisms out of the sinuses and nose
  • Overproduction of mucus

Sinusitis is an extremely common problem. In a given year, about 37 million Americans suffer from sinusitis.

What are the risk factors for sinusitis?
What are the symptoms of sinusitis?
How is sinusitis diagnosed?
What are the treatments for sinusitis?
Are there screening tests for sinusitis?
How can I reduce my risk of sinusitis?
What questions should I ask my doctor?
Where can I get more information about sinusitis?


Alho OP. Vital infections and susceptibility to recurrent sinusitis. Curr Allergy Asthma Rep. 2005;5:477-481

Rakel RE, Bope ET. Conn’s Current Therapy. 54th ed. Philadelphia, PA: WB Saunders Company; 2002.

Sinus infection (sinusitis). National Institute of Allergy and Infectious Diseases website. Available at: Accessed September 12, 2008.

Last reviewed July 2008 by Elie Edmond Rebeiz, MD, FACS

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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