Most common complication of Sinusitis is
Orbital cellulitis is an infection of the soft tissues of the orbit posterior to the orbital septum. Orbital cellulitis is caused most commonly in all age groups by ethmoid sinusitis. The organisms gain access to the orbit through thin bones of the orbital walls, venous channels, foramina, and dehiscence. Orbital cellulitis resulting from infection of the maxillary sinus secondary to dental infections can be caused by microorganisms indigenous to the mouth.
Orbital cellulitis
Meningitis
Brain abscess
Septicemia
Nose and paranasal sinuses