Sinusitis is inflammation of the sinuses, which are cavities, or air-filled pockets, near the nasal passage. It usually occurs after a cold or an allergic inflammation. The inside of the sinuses is similar to the inside of the nose. There are four types of sinuses: Ethmoid sinus: Located inside the face, around the area of the bridge of the nose. This sinus is present at birth and continues to grow. Maxillary sinus: Located inside the face, around the area of the cheeks. This sinus is also present at birth and continues to grow. Frontal sinus: Located inside the face, in the area of the forehead. This sinus does not develop until around seven years of age. Sphenoid sinus: Located deep in the face, behind the nose. This sinus does not develop until adolescence. There are four types of sinusitis: Acute: Symptoms last less than four weeks and get better with the appropriate treatment. Subacute: This type of infection doesn’t get better with treatment initially, and symptoms last four to eight weeks. Chronic: This type of infection happens with repeated acute infections or with previous infections that were inadequately treated. These symptoms last eight weeks or longer. Recurrent: In this case, three or more episodes of acute sinusitis occur per year. Sometimes, a sinus infection happens after an upper respiratory infection (URI) or common cold. The URI causes inflammation of the nasal passages that can lead to obstruction of the opening of the paranasal sinuses, which can cause infection in the sinuses. Allergic disease can also lead to sinusitis because of the swelling of the nasal tissue and increased production of mucus. There are other possible conditions that can block the normal flow of secretions out of the sinuses and can lead to sinusitis. These may include abnormalities in the structure of the nose, nasal polyps, enlarged adenoids, diving and swimming, infections from a tooth, trauma to the nose, foreign objects that are stuck in the nose, gastroesophageal reflux disease (GERD), or secondhand smoke. After the blockage of the flow of secretions from the sinuses, bacteria will sometimes begin to grow. This leads to a sinus infection, or sinusitis. Usually, your physician can diagnosis sinusitis based on your symptoms and a physical exam. In some situations, additional tests may be performed to confirm the diagnosis. These may include cultures from the nose, sinus X-rays, computed tomography (CT or CAT scan), cultures from the sinus fluid, or blood tests. Treatment of sinusitis may include nasal drops as well as acetaminophen for pain or discomfort. Decongestants and antihistamines don’t seem to help the symptoms of sinusitis. Antibiotics may be withheld for 10 to 14 days, unless severe symptoms develop, such as fever, facial pain or tenderness, or swelling around the eye. Surgery should be considered only if other treatments have failed. Referral to an allergist/immunologist is often needed, particularly for people with chronic or recurrent sinusitis and for those who have had sinus surgery but still experience sinusitis.