A number of factors predispose one to sinusitis. The most common situation occurs when a viral upper respiratory infection (in other words, a cold) causes swelling and congestion of the lining of the nose. This may result in obstruction of the relatively small sinus openings, decreasing normal sinus ventilation and drainage. That triggers the development of a sinus infection. Sinusitis may begin as a viral infection, but within a few days can progress to a bacterial infection, with pus in the sinus. Pus is a thick material that causes further sinus blockage. This blockage leads to infection, with increased mucus production. This excess of mucus and pus is moved by the cilia that line the sinuses and nose into the back part of the nose, causing the postnasal drip which accompanies almost all cases of sinusitis.

In many sinus sufferers, especially those with repeated infection, there may be one or more preexisting conditions that contribute to the problem. These include a deviated nasal septum, nasal polyps, or allergies. All of these cause narrowing of the nasal passages, and often blockage of the sinus openings, which increase the chance of a viral cold progressing to a full-blown sinus infection. This is why some people undergo operations such as a deviated septum surgery or nasal polyp removal -- to improve their chronic sinus infections. Likewise, I see a number of patients whose sinus infections stopped once they began allergy shots, which addresses the allergic component of their sinus disease.

Several specific conditions trigger sinus infections. 

I will address these briefly because they are common scenarios that send patients to my office, and thus may be contributing factors in your sinus problems.

Dental Problems

At least several times a year I see a patient with an infected tooth, usually an upper, that leads to infection in the maxillary sinus. Remember that the upper teeth, especially the molars, are located just below the maxillary sinuses. The bony wall between the roots of the molars and the floor of the maxillary sinus may be quite thin, and an infection that begins in your teeth can travel to the adjacent sinus. This also explains why one of the symptoms of acute maxillary sinusitis can be pain in the upper teeth.

Flying and Diving

Some people get severe sinus attacks following airplane flights or scuba diving because of underlying problems with nasal drainage. When you fly or deep-dive, you experience changes in air pressure. You have probably noticed these pressure changes in your ears during an airplane takeoff. This is because the eustachian tube between your nose and ears functions to equalize these pressure changes so that they wont damage your head and its intricate structures. This is what gives you the ear-popping feeling when driving uphill, riding in an elevator, or flying in an airplane. Pressure changes can cause swelling of the sinus membranes and lead to inflammation and, at times, to infection. If you have a cold, these problems become worse. An easy remedy I give my patients is an oral decongestant like Sudafed to be taken a half hour before the plane takes off (or before scuba diving), and a topical decongestant nasal spray (such as Afrin or Neo-Synephrine) during ascent and descent (and mid-flight for longer trips). The decongestants keep the nasal passages open and help prevent blockage. For infants and young children, who dont know how to clear their ears, give them a bottle or encourage swallowing while the plane is landing.


During pregnancy, many women experience "rhinitis of pregnancy" (inflammation of the nose), which is characterized by swelling of the nasal lining, with associated mucus drainage. This condition is due to hormonal changes that occur during pregnancy. Interestingly, individuals who take birth control pills (which cause the body to mimic the hormonal state of pregnancy) may also experience nasal symptoms. As with anything that causes swelling of the nasal membranes, rhinitis of pregnancy may lead to a sinus infection. This can be problematic to treat because there are limitations to medications an expectant mother can take. While most physicians are reluctant to prescribe much medication for pregnant women, the use of a saltwater nasal spray or a nonprescription decongestant spray to open the nasal passages may be acceptable. If infection develops, then an antibiotic may be necessary. If you are pregnant, check with your obstetrician before taking any medication.

Immunosuppressed Patients

As medical treatment becomes more sophisticated, we see an increasing number of patients who are "immunosuppressed," or have poorly functioning immune systems. These include patients on chemotherapy or radiation therapy, and those who have had organ transplants. AIDS and HIV-positive patients also have weakened immune systems and may be unable to fight the typical sinus infection. Any of these patients should be under close medical care during treatment for sinus infections. If sinus infections are left untreated, serious complications can result, with the infection spreading to nearby structures, including the eye or the brain. Additionally, immunocompromised patients can have unusual types of organisms growing in their sinuses, such as fungus, which can be destructive; these must be treated aggressively.


Asthma is a disease of lower-lung airway sensitivity to a variety of stimuli. Asthma sufferers are more likely than the average person to have sinus problems. If you have asthma, you may also have hyperactive nasal airways, which lead to sinusitis or nasal polyps. Allergies are also commonly present with asthma and sinusitis, and thus it is felt that the two are interrelated diseases. In addition, patients with asthma may be sensitive to the dripping from a sinus infection. The infected pus that drips from your nose into your throat can exacerbate or set off an asthma attack. It is important for patients with asthma to seek medical attention with early signs of a sinus infection to prevent their asthma from getting worse.