The medical name for hayfever is allergic rhinitis - this means an allergy affecting the nose.
This allergy may be either seasonal, such as in spring when there is plenty of pollen or new plant growth which causes the allergy; or perennial which means all year round, when you are allergic to dust, pet hair or other irritant substances. The severity and type of hayfever varies from person to person, but can make you miserable if not treated and the symptoms prevented.