What is sinusitis?

Sinusitis, also known as a sinus infection or rhinosinusitis, is an inflammation of the mucous-lined, air-filled spaces in your skull that connect to the nose and throat.  When the sinuses become inflamed, blocked or swollen, normal mucus drainage may not occur trapping air and other fluids, creating vacuums and/or pressure. This pressure can cause pain, which can sometimes be intense.  Clogged sinuses may also lead to infections.