What causes a sinus infection?

Sinusitis, or a sinus infection, occurs when the sinuses and nasal passages become inflamed. Most sinus infections are caused by a virus. Sinus infections are rarely caused by bacteria. Other causes of sinusitis include:

  • allergies
  • pollutants (airborne chemicals or irritants)
  • fungal infections
  • structural problems within the nasal cavity
  • a weak immune system
Dr. Marilene B. Wang, MD
Ear, Nose & Throat (ENT Specialist)

Frequent sinus infections often signify underlying inflammation in the nose and sinuses. This may happen in people with chronic allergies. There may be a structural reason for frequent sinus infections, such as polyps or a deviated septum, which blocks mucus from draining out of the sinuses. The mucus then accumulates and causes an infection.

Your immune system is also important in determining whether you get sinus infections. If you are not getting enough sleep or taking good care of your overall health, your immune system may be suppressed, making you prone to sinus infections. To avoid frequent sinus infections, it's important to keep yourself healthy, control any allergies and make sure that your immune system is healthy.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.