What is sinusitis?

Sinus infection (sinusitis) is an inflammation of the mucous membranes that line the sinus cavities.  This inflammation causes the mucous glands in the sinuses to secrete more mucus.  When the passages in the sinuses become blocked, pressure develops, and the nose may feel plugged. Sinusitis can be caused by a virus, allergic rhinitis (hay fever), chronic rhinitis, deviated nasal septum or polyps, and may run in families. Irritants, air pollution, smoke, and fumes may also cause inflammation and lead to bacterial growth and infection.

Acute sinusitis is generally caused by a bacterial infection. Chronic sinusitis may not be associated with infection but may be due to other problems as mentioned above.  Symptoms may also occur which do not respond to medical treatment.

Chronic sinusitis may produce fewer symptoms such as chronic sore throat and cough, particularly when reclining, decreased sense of smell, bad breath, nasal congestion, and a low grade fever (less than 101 degrees F).  In chronic sinusitis, the symptoms are often more subtle.  Some people just have drainage, sore throat, or a cough that lasts for days to weeks.

Fungal infections cause a stuffy nose, eventually causing the nasal passages and sinuses to swell shut. In the body, any time something gets blocked (e.g., appendix, gallbladder, etc.), it results in a secondary bacterial infection - and the sinuses are no exception. When this happens, your nasal mucus turns yellow-green, and you go to the doctor in pain. They give you an antibiotic, which knocks out the bacterial infection and sometimes leaves you feeling better. Unfortunately, the antibiotic worsens the underlying yeast infection in your nose, causing more swelling and blockages and, therefore, more attacks of bacterial infections. This is why sinusitis in the U.S. usually becomes chronic. An interesting study reported in the Mayo Clinic Proceedings noted that previously "fungus allergy was thought to be involved in less than 10% of cases... our studies indicate, in fact, fungus is likely the cause of nearly all of these problems and that it is not an allergic reaction but an immune reaction."

Sinusitis is an infection or inflammation of the mucous membranes that line the inside of the nose and facial sinuses. Facial sinuses are hollow spaces, or cavities, located in the skull around the eyes, cheeks, and nose.

When a mucous membrane becomes inflamed, it swells, blocking the drainage from the sinuses into the nose and throat and causing pressure and pain in the sinuses. Bacteria are more likely to grow in sinuses that are unable to drain properly. Symptoms may include pain and pressure in the face, yellow or greenish discharge from the nose, nasal congestion, and sometimes a fever, a chronic cough that produces mucus, and a reduced sense of taste or smell.

Sinusitis often improves on its own, but it may need to be treated with antibiotics or other medications if symptoms are severe or last longer than 4 weeks.

Sinusitis is a common condition in which the sinuses—the four cavities around the nasal passages—become inflamed and swollen. This causes mucus buildup that makes it difficult to breathe through your nose. Sinusitis can be acute (lasting up to 4 weeks), sub-acute (lasting from 4 to 12 weeks), or chronic (lasting 12 weeks or longer despite treatment). Besides difficulty breathing, the condition can cause pain and swelling around your eyes, nose, cheeks, and forehead, and a throbbing headache.

Approximately 30 million Americans (one in seven) suffer from acute sinusitis each year. Some experience several bouts a year, and many have a chronic problem. Sinusitis is more common in adults than children.

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The sinuses are air-filled spaces above, between, and beneath your eyes, flanking your nose. Both the nose and sinuses are lined with a thin membrane that swells and produces mucus in response to irritation. Normally, the mucus from the sinuses drains through small openings, known as ostia, which connect the sinuses to the nasal passages.