A sinus is a hollow space in the body. There are many types of sinus, but sinusitis affects the paranasal sinuses, the spaces behind the face that lead to the nasal cavity. Sinusitis occurs when mucus builds up and the sinuses become inflamed.

Symptoms of Sinusitis

• Nasal obstruction or congestion
• Hyposmia (reduced sense of smell)
• Facial pressure, pain, tenderness
• Rhinorrhoea (anterior or postnasal)
• Fever or malaise (acute infection)
• Toothache (upper teeth)

Timescale for rhinosinusitis

• Acute: <4 weeks
• Sub acute: 4-12 weeks
• Chronic: >12 weeks
• Acute exacerbation: sudden worsening of chronic sinusitis with return to baseline after  treatment.