What causes sinus pain and congestion? “The number one cause is allergies,” says Jyoti Gopal, MD, a family practice physician with the Lehigh Valley Health Network in Bethlehem, Pennsylvania. Some people have seasonal allergies and are bothered most during the spring and fall, when the pollen counts are high, she says, while others have year-round allergies that continually trigger their sinus pain and congestion. The second leading cause is the common cold or flu, Dr. Gopal says. A cold, which is caused by a virus, can turn into a sinus infection. The cold virus attacks the lining of your sinuses, which respond by swelling; this results in narrowing of the drainage pathways in the sinuses and nose, according to the American Academy of Otolaryngology — Head and Neck Surgery. In response, you produce more mucus, which gets blocked in your swollen sinuses. Bacteria like to grow where the mucus builds up and sometimes cause a lingering sinus infection — an infection can linger even after the cold virus is gone. Other causes of sinus pain, pressure, and congestion include:

Pollutants. Air pollution, cigarette smoke, and chemical irritants such as pesticide sprays and household cleaners can inflame the sinus linings.

Polyps. These are sac-like growths of inflamed tissue on the lining of the sinuses.

Anatomical issues. A structural problem such as a deviated septum or nasal bone spur can prevent mucus from draining out of the sinus, Gopal says.

Fungi. This is a growing problem, especially in people with weakened immune systems from conditions such as AIDS, leukemia, and diabetes. Fungi, just like bacteria, can cause a sinus infection, but will not respond to antibiotics. The most common fungus associated with sinusitis is aspergillus, according to the University of Maryland Medical Center.

Swimming or diving. These activities can increase your risk for sinusitis because of pressure changes in the nose and sinuses.

Sinus Pain and Congestion: How to Avoid It Can you prevent sinus pain and congestion? Probably not altogether, Gopal says, but you can take these steps to keep infections and allergens at bay: Sinus pain can be worse for people with allergies and weakened immune systems, but following a healthy lifestyle and practicing good hygiene could save you from bothersome sinus pain and congestion.