The common cold virus is the most common cause of acute sinusitis. Bacterial sinusitis is usually caused by Haemophilus influenzae, and less commonly by Streptococcus pneumoniae, Staphylococcus aureus, Streptococcus pyogenes, or anaerobic bacteria. Chronic sinusitis is most commonly caused by Staphylococcus aureus or multiple bacteria, while fungal sinusitis is most commonly seen in immunocompromised patients and caused by Aspergillus.[1] Physiologically, sinusitis develops when clearance of mucus is impaired and and the nasal cavity is abnormal or not functioning properly.[2]
What causes sinusitis?
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•Last Updated: May 16, 2025
Acute sinusitis is primarily caused by the common cold virus, whereas bacterial sinusitis is often due to Haemophilus influenzae and other bacteria. Chronic sinusitis is typically aassociated with Staphylococcus aureus or multiple bacteria, and fungal sinusitis occurs mainly in immunocompromised individuals and is often caused by Aspergillus.