Introduction Infection of the paranasal sinus due to undrained collection of pus maxillary sinuses most commonly involved in adults ethmoid sinuses most commonly involved in children Etiologies acute viral respiratory tract infection smoking septal deviation diabetes ketoacidosis be associated with mucormycosis infection Common pathogens Viruses S. pneumonia Haemophilus influenzae Moraxella cattarrhalis anaerobes (e.g bacteroides) fungi (aspergillus, mucormycosis) Presentation Symptoms fever facial pain (over infected sinus) headache purulent rhinorrhea Physical exam facial tenderness with palpation Evaluation CT most sensitive test Treatment Medical decongestants analgesics saline irrigation avoid antibiotics early in symptom course unless high risk patient most infections are viral in origin consider after 10 days of symptoms empiric antibiotic should cover most common organisms (listed above) little data supporting use of systemic corticosteroids Prognosis, Prevention, and Complications Most resolve with supportive treatments Extra-sinus complications orbital abscess, meningitis, epidural abscess, brain abscess Can be fatal in diabetic or immunocompromised patients