Letting a chronic sinus infection go untreated is not a good idea. The consequence depends on what the cause is. There could be some minimal problems such as prolongation of symptoms where the patient might have difficulty in working or might be easily irritable if the symptoms are not controlled. In serious situations like in fungal sinusitis or bacterial sinusitis, the bone between the eye and the nose or the brain and the nose might get eaten off by the disease where the brain and the eye gets exposed to the fungus or the bacteria, which is not such a safe situation. In certain situations like the patients upper respiratory tract infections like the nose and the paranasal sinus infection, might trigger the nose and the lower respiratory tract and induce an asthmatic attack if the upper respiratory tract infection is not controlled. Hence it would be a good idea to control the paranasal sinus disease.