Skip navigation

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

URL of this page: //medlineplus.gov/ency/imagepages/19315.htm

Sinusitis

Sinusitis

Overview

Sinusitis refers to inflammation of the sinus cavities, which are moist, hollow spaces in the bones of the skull. There are four pairs of sinuses:

  • Frontal sinuses
  • Maxillary sinuses
  • Ethmoid sinuses
  • Sphenoid sinuses (not shown in illustration)

If the opening from a sinus cavity becomes plugged, the flow of mucus is blocked and pressure builds up, causing pain and inflammation.

Review Date 5/2/2024

Updated by: Josef Shargorodsky, MD, MPH, Johns Hopkins University School of Medicine, Baltimore, MD. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.