They keep the air you breathe wet. Your sinuses can't drain right if they are infected and swollen. Your doctor can tell if you have a sinus infection with a physical exam, a laboratory study of a sample of your nasal discharge, and X-rays of the sinuses. These work to clear the infection and reduce congestion. Severe cases may require surgery to drain the sinuses.
Wet air helps make mucus thin.
You can put a warm washcloth or compress on your face, too. This can help with the pain. Use nose drops only for the number of days prescribed. Repeated use of them creates a dependency. To avoid picking up germs, never borrow nose drops from others.