Sinusitis is inflammation of the sinuses, most commonly caused by a viral or bacterial infection or by an allergy.
Sinusitis is one of the most common medical conditions. About 10 to 15 million people each year develop symptoms of sinusitis. Sinusitis may occur in any of the four groups of sinuses: maxillary, ethmoid, frontal, or sphenoid. Sinusitis nearly always occurs in conjunction with inflammation of the nasal passages (rhinitis), and some doctors refer to the disorder as rhinosinusitis. It may be acute (short-lived) or chronic (long-standing).
Sinusitis is defined as acute if it is totally resolved in less than 30 days. In people who have a normally functioning immune system, acute sinusitis is usually caused by a viral infection. Sometimes sinusitis is caused by bacteria. Infection often develops after something blocks the openings to the sinuses. Such blockage commonly results from a viral infection of the upper airways, such as the common cold. During a cold, the swollen mucous membranes of the nasal cavity tend to block the openings of the sinuses. Air in the sinuses is absorbed into the bloodstream, and the pressure inside the sinuses decreases, causing pain and drawing fluid into the sinuses. This fluid is a breeding ground for bacteria. White blood cells and more fluid enter the sinuses to fight the bacteria. This influx increases the pressure and causes more pain.
Allergies also cause mucous membrane swelling, which blocks the openings to the sinuses. Additionally, people with a deviated septum are more prone to blocked sinuses.
Sinusitis is defined as chronic if it has been ongoing for more than 90 days. Doctors do not understand exactly what causes chronic sinusitis, but it involves factors that cause chronic inflammation. Factors include chronic allergies, nasal polyps, and exposure to environmental irritants (such as airborne pollution and tobacco smoke). Often the person has a family history, and a genetic predisposition seems to be a factor. Sometimes the person has a bacterial or fungal infection, in which case the inflammation is much worse. Occasionally, chronic sinusitis of the maxillary sinus results when an upper tooth abscess spreads into the sinus above.
Acute sinusitis usually results in pain, tenderness, congestion and blockage in the nose, reduced ability to smell (hyposmia), bad breath (halitosis), a productive cough (especially at night), and swelling over the affected sinus. Maxillary sinusitis causes pain over the cheeks just below the eyes, toothache, and headache. Frontal sinusitis causes headache over the forehead. Ethmoid sinusitis causes pain behind and between the eyes, tearing, and headache (often described as splitting) over the forehead. Sphenoid sinusitis causes pain that does not occur in well-defined areas and may be felt in the front or back of the head.
In acute sinusitis, yellow or green pus may be discharged from the nose. Fever and chills also can occur, but their presence may suggest that the infection has spread beyond the sinuses.
The symptoms of chronic sinusitis are similar to those caused by acute sinusitis, but pain may be less severe. The most common symptoms of chronic sinusitis are nasal obstruction, nasal congestion, and postnasal drip. People with sinusitis may have colored discharge and a decreased sense of smell. A person also may feel generally ill (malaise).
Complications of sinusitis:
The main complication of sinusitis is spread of a bacterial infection. An infection may spread to the tissues around the eye (see Infections of the Orbit (Preseptal Cellulitis; Orbital Cellulitis)) and cause changes in vision or swelling around the eye. Less commonly, the infection spreads to involve the eye itself, causing eye pain and disturbing vision. An infection in the eye can quickly—within minutes to hours—result in blindness. Less often, an infection can spread to tissues around the brain (meningitis―see Meningitis) and cause severe headache and confusion. People with sinusitis who develop such symptoms should be evaluated by a doctor as soon as possible.
A doctor bases the diagnosis on the typical symptoms. A computed tomography (CT) scan is able to determine the extent and severity of sinusitis but is done mainly when people have symptoms of complications (such as a red, bulging eye) or when people have chronic sinusitis. If a person has maxillary sinusitis, the teeth may be x-rayed to check for a tooth abscess. Sometimes a doctor passes a thin viewing scope (endoscope) into the nose to inspect the sinus openings and to obtain samples of fluid for culture. This procedure, which requires a local anesthetic (to numb the area), can be done in the doctor's office.
Sinusitis in children is suspected when a pus-filled discharge from the nose persists for more than 10 days along with extreme tiredness (fatigue) and cough. Pain or discomfort in the face may be present. Fever is uncommon. When examining the nose, a doctor sees pus-filled drainage. A CT scan can confirm the diagnosis but, because of concerns about radiation exposure, is usually done only in children with chronic sinusitis that does not resolve with antibiotic treatment or with signs of complications.
Treatment of acute sinusitis is aimed at improving sinus drainage and curing the infection. Steam inhalation; hot, wet towels over the affected sinuses; and hot beverages may help relieve the swollen membranes and promote drainage. Flushing a saltwater solution through the nose (nasal irrigation) or using a salt-water spray also can help symptoms. Nasal sprays, such as phenylephrine or oxymetazoline, which cause swollen membranes to shrink, can be used for a limited time. Similar drugs, such as pseudoephedrine, taken by mouth are not as effective. Corticosteroid nasal sprays also can help relieve symptoms but take at least 10 days to work. For acute sinusitis that is severe or persistent, antibiotics such as amoxicillin/clavulanate, doxycycline, or levofloxacin are given.
People who have chronic sinusitis take the same antibiotics but for a longer period of time, typically 4 to 6 weeks. When antibiotics are not effective, surgery may be performed either to wash out the sinus and obtain material for culture or to improve sinus drainage, which allows the inflammation to resolve.
Last full review/revision September 2014 by Marvin P. Fried, MD