Common causes of chronic sinusitis include:

  • Nasal polyps. These tissue growths may block the nasal passages or sinuses.
  • Allergic reactions. Allergic triggers include fungal infection of the sinuses.
  • Deviated nasal septum. A crooked septum — the wall between the nostrils — may restrict or block sinus passages.
  • Trauma to the face. A fractured or broken facial bone may cause obstruction of the sinus passages.
  • Other medical conditions. The complications of cystic fibrosis, gastroesophageal reflux, or HIV and other immune system-related diseases may result in nasal blockage.
  • Respiratory tract infections. Infections in your respiratory tract — most commonly, colds — can inflame and thicken your sinus membranes, block mucus drainage and create conditions ripe for growth of bacteria. These infections can be viral, bacterial or fungal in nature.
  • Allergies such as hay fever. Inflammation that occurs with allergies may block your sinuses.
  • Immune system cells. With certain health conditions, immune cells called eosinophils can cause sinus inflammation.
Jul. 02, 2013

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