Do you wish to know when are sinus infections contagious? When they are caused due to bacteria or viruses, they can become contagious. There are several instances in which people who are close to the patients have picked similar symptoms. Since these conditions are accompanied with cough and sneezing, the virus or bacteria travels in the air and infects others. However, there are several ways of avoiding the same and these are quite simple. Washing your hands regularly, not using the patients’ towels and wearing masks are some of the most common preventive steps to be followed.