When your nasal passages become infected, that’s a sinus infection. And they’re harder to get rid of. Viruses, bacteria, or even allergies can lead to sinus infections.

Colds don’t usually cause sinus infections, but they do offer a breeding ground for them.

You touch your nose a lot when you’re sick, and each time you bring more bacteria to the sinuses because your sinuses can’t drain, the bacteria stay there and grow.