Needless to say, with all these symptoms it can be difficult to concentrate and headaches are not unusual. Hay fever has been desribed as 'asthma of the nose' and indeed approximately one in five people with hay fever also has asthma. Although hay fever has long been associated with the time of year when hay was made, it is not in fact an allergy to hay. The cause of hay fever was established in the last century by Dr Charles Blackley to be an allergy to grass pollen. More recent studies have found that grass pollen is not the only culprit when it comes to triggering hay fever symptoms.
Hay fever is the most common form of rhinitis and is also known as 'seasonal allergic rhinitis'.
The seasonal allergens mainly responsible for causing hay fever are the very light pollen grains from wind-pollinated trees, grasses and weeds. More than 30 different pollens are in the air at different times of the year. The pollen from birch trees gets into the air as early as March and causes symptoms in about one-quarter of people who are already allergic to grass pollen. At the other end of the season, the pollen from weeds, particularly stinging nettle, can also affect some people causing their symptoms to carry on well into August, long after symptoms have finished for those allergic to grass pollen alone. The grass pollen season stretches from May to August with pollen counts being highest around mid-June to early July.