Sinusitis is the swelling of the mucous membrane in the paranasal sinuses. Respiratory viruses causing the common cold or flu, can lead to acute sinusitis. If the condition lasts longer than three months, it is considered as chronic sinusitis. When one has a cold, the nose is no longer sufficiently ventilated and the secretion that does not run off anymore can cause the swelling of the mucous membrane of the nose and the paranasal sinuses. Typical symptoms are a blocked nose and cough, fever, swelling and pus collection. Pain often occurs in the forehead, jaw or around the eyes and typically the head hurts badly when bending over too quickly.