A sinus infection in most cases is almost harmless, although you do become uncomfortable and sometimes experience pain. If symptoms become very severe, antibiotics generally eliminate further problems. In rare cases, however, sinusitis can be very serious and can occur with complications.
The most common complication of sinusitis is chronic sinusitis. This can develop from severe cases of acute sinusitis. The symptoms of this complication are almost the same as to those of the acute condition, but they last longer and can keep coming back within a long period of time.