Acute sinusitis may be caused by a variety of bacteria and often develops after a viral infection of the upper airways, such as the common cold. Occasionally, chronic sinusitis of the maxillary sinus results from a tooth infection. During a cold, the swollen mucous membrane of the nasal cavity tends to block the openings of the sinuses. If the vacuum remains, fluid is drawn into and fills the sinuses, creating a breeding ground for bacteria. For example, maxillary sinusitis produces pain over the cheeks just below the eyes, toothache, and headache.
Frontal sinusitis produces headache over the forehead.
Ethmoid sinusitis produces pain behind and between the eyes and headache, often described as splitting, over the forehead. The pain produced by sphenoid sinusitis doesn't occur in well-defined areas and may be felt in the front or back of the head. Fever and chills suggest that the infection has spread beyond the sinuses. The nasal mucous membrane is red and swollen, and yellow or green pus may be discharged from the nose. If a person has maxillary sinusitis, the teeth are x-rayed to check for tooth abscesses.