What Happens

There are two types of sinusitis: acute (sudden onset) and chronic (long-term). Sinusitis often develops after a cold or viral infection. Most sinus infections improve on their own, but sometimes they develop into a bacterial infection—swelling, inflammation, and mucus production caused by the cold can lead to blockage in the nasal passages, which may encourage the growth of bacteria.

Acute sinusitis, whether viral or bacterial, may develop into chronic inflammation or infections that may last 8 weeks or longer. Chronic sinusitis can lead to permanent changes in the mucous membranes that line the sinuses. As a result of these changes, you may become prone to having more sinus infections that may become more difficult to treat.

Complications of sinusitis (such as an infection of the facial bones called osteomyelitis) are relatively rare. But when complications occur, they may be life-threatening and often require extensive medical or surgical treatment.

What Increases Your Risk

Your risk of sinusitis increases if you have recently had a cold, another viral or bacterial infection, or an upper respiratory tract infection. Also, chronic nasal allergies (allergic rhinitis) can lead to sinusitis.

Sometimes a deviated septum, broken nose, or growths such as nasal polyps can make you more susceptible to sinus infections. Problems with nasal structure can prevent the proper flow of mucus from the sinuses into the nose.

Other factors that increase your risk for getting sinus infections include smoking, air pollution, overuse of decongestant sprays, cold weather, rapid air pressure changes (such as from flying or scuba diving), and swimming in contaminated water. Also, using continuous positive airway pressure (CPAP) to treat sleep apnea may increase the risk of sinusitis.