Allergic rhinitis, known as hay fever, is cause by pollens of specific seasonal plants, airborne chemicals and dust particles in people who are allergic to these substances. It is characterised by sneezing, runny nose and itching eyes. This seasonal allergic rhinitis is commonly known as 'hay fever', because it is most prevalent during haying season. It is particularly prevalent from late May to the end of June (in the Northern Hemisphere). However it is possible to suffer from hay fever throughout the year.