Hay fever, seasonal allergic rhinitis (SAR), is an allergic reaction that occurs when the immune system overreacts to substances that have been inhaled. There are two main types of allergic rhinitis, seasonal and persistent. Hay fever is the common term used to describe seasonal allergic rhinitis. SAR is an allergic reaction that is triggered by the airborne pollens of specific seasonal plants such as trees, weeds, mould and, much more commonly, grasses.
Persistent Allergic Rhinitis, which usually occurs all year round, is caused by indoor allergens such as dust mites, dander shed from the coats of household pets, or indoor mould.
Allergic rhinitis affects between 10% and 25% of the worlds population, and this number appears to be increasing.
Rhinitis is inflammation of the mucosal membrane in the nose. Symptoms, which can be mild or severe, include:
- itching of the nose, palate, throat (oropharynx) and ears
- runny nose (rhinorrhoea)
- nasal congestion
Hay fever is often accompanied by conjunctivitis, which is inflammation of the mucosal membrane that lines the exposed portion of the eye. Symptoms of conjunctivitis include irritation, itching and watering of the eye.
Some sufferers may also experience facial pain, headache, loss of concentration and symptoms of asthma, including difficulty breathing, wheezing and tightness in the chest.