Allergic rhinitis is a condition which presents as frequent attacks of sneezing, nasal discharge or blockage of the nasal passages. It may be seasonal (a limited period of the year) or perennial (throughout the whole year).
Seasonal rhinitis is often called "hay fever" and is the most common of all allergic diseases. From 2 to 20 per cent of the population worldwide are thought to be affected by it. Prevalence is maximum in the teenage years; when up to 30 per cent of young people suffer symptoms in the summer months.