is a medical term used to describe inflammation (swelling and irritation) of one or more of the sinuses. It is a common illness in both children and adults.
Most sinus infections
are caused by a virus. This is known as acute viral sinusitis. Bacteria can also infect the sinuses, although this is less common. Bacteria cause up to 13 percent of acute sinus infections in children.
Because infections are the main cause of sinusitis, the terms "sinusitis" and "sinus infection" are often used interchangeably.
The paranasal sinuses are hollow air spaces located within the skull. They include the frontal, maxillary, ethmoid, and sphenoid sinuses. These sinuses connect to the nasal passages through an opening that allows movement of air and mucus in between the nose and sinuses.
It can take up to 20 years for the paranasal sinuses to completely develop. However, in most children, by age 12, the sinuses are almost completely developed and have reached adult proportions.