Sneaky causes of sinus trouble

Sinus infections strike about 37 million people in the U.S. each year.

Teeny holes that connect your nasal passages to your sinuses (basically a collection of hollow, moist cavities that lurk beneath your nose, eyes, and cheeks) get blocked. Then gunk builds up in your sinuses, germs may grow, and you feel, well, hideous.

But the cause of the blockage is sometimes trickier to figure out. Here are 13 things that can cause an acute sinus infection (the most common type) and, in some cases, lead to a chronic sinus infection.

1. Viruses

Most sinus infections start with a cold. Colds are caused by a virus, which can make nasal tissue swell, blocking the holes that normally drain sinuses.

If your sinus infection is caused by a virus, antibiotics won’t help since these drugs kill only bacteria. Your symptoms will probably get better after about a week or so. A decongestant can help, but don’t use it for more than four or five days to avoid becoming dependent.

The best defenses against these sinus infections are the same things that protect against colds and the flu. In other words, get a flu shot, wash your hands, and don’t chill with the visibly ill.

2. Allergies

Because inflammation can block the nasal passages and prevent draining, allergies are often associated with sinus infections. In fact, studies have shown that people with sinus infections who have allergies tend to have more extensive sinusitis, says Dr. Sonia Bains, assistant professor in the Division of Pulmonary, Critical Care, Allergy, and Sleep Medicine at the Medical University of South Carolina.

If you’re prone to allergies or hay fever, avoid things that trigger allergic reactions, such as dust mites, pet dander, mold, and cockroaches. Prescription or over-the-counter antihistamines and prescription nasal sprays can reduce chronic inflammation in the sinuses and nasal lining.

3. Bacteria

If a cold does not resolve in 10 to 15 days, bacteria may have joined the party.

Bacterial infections rarely jump-start sinus infections, but they are almost always the cause of complicating, secondary infections, says Dr. William J. Hueston, professor and chair of the Department of Family Medicine at the Medical University of South Carolina, in Charleston. In these cases, it's most likely Streptococcus pneumoniae or Haemophilus influenzae.

These bacteria lurk in healthy people; they’re waiting for the right circumstances to grow. Take a decongestant during a cold to avoid those circumstances. If you do develop bacterial sinusitis, you can treat it with antibiotics.