The backed-up mucus collects viruses or bacteria. The resulting pressure and swelling can cause facial pain, headaches, toothaches, and postnasal drip. Postnasal drip occurs when mucus leaks from the back of the nose to the throat. It can also be caused by an allergy to dust, plants, air pollution, or tobacco smoke. Swimming in contaminated water also can cause sinusitis, usually from infection by bacteria or sometimes as a result of protists, such as algae, in the water.
Untreated sinusitis can be serious.
It can lead to an ear infection, bronchitis , or pneumonia . Incidence Some 20 million Americans each year develop inflamed and painful sinuses. Symptoms you are likely to notice An attack of sinusitis most often begins with a cold that lasts for more than a week. The sinusitis is accompanied by a nasal discharge. If your eye bulges and is red and painful, go to your doctor right away.