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. Acute sinusitis may be caused by a variety of bacteria and 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 obstructed sinuses.
Sinusitis is defined as chronic if it has been ongoing for more than 8 to 12 weeks. Doctors do not understand exactly what causes chronic sinusitis, but it may follow a viral infection, a severe allergy, or exposure to an environmental pollutant. Often the person has a family history, and a genetic predisposition seems to be a factor. If the person has a bacterial or fungal infection, 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 obstruction 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, a bacterial infection of the skin around the eye socket (periorbital cellulitis), 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. Any change in vision or swelling around the eye is a very serious condition that can quickly—within minutes to hours—result in blindness. Such a change should be evaluated by a doctor as soon as possible. Often, pain is more severe in acute sinusitis.
The symptoms of chronic sinusitis are similar to those caused by acute sinusitis. 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).
A doctor bases the diagnosis on the typical symptoms and, sometimes, on x-ray studies. X-rays may show fluid in the sinuses, but a computed tomography (CT) scan is better able to determine the extent and severity of sinusitis. If a person has maxillary sinusitis, the teeth may be x-rayed to check for tooth abscesses. 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.
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 tightened or constricted blood vessels and promote drainage. Nasal sprays, such as phenylephrine, which cause blood vessels to narrow (constrict), can be used for a limited time. Similar drugs, such as pseudoephedrine, taken by mouth are not as effective. For acute sinusitis, antibiotics such as amoxicillin or trimethoprim/sulfamethoxazole are given.
People who have chronic sinusitis take antibiotics, such as amoxicillin/clavulanate or cefuroxime, for a longer period of time. 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 July 2008 by Marvin P. Fried, MD; Michael Jacewicz, MD