A nasal obstruction is anything that prevents the flow of air into and out of the nose. The blockage could be in one or both nasal passages, but it is temporary in most cases. Causes of nasal obstruction include sinusitis, allergies, viral infection, nasal polyps, deviated septum and benign or cancerous tumors. Treatments for nasal obstructions depend on the cause and include nasal sprays, antibiotics, steroids, antihistamines or surgery. To learn more, click here.