Hay fever and allergic rhinitis
Allergic rhinitis is caused when the body makes allergic antibody (IgE) to a substance such as pollen, house dust mites, cat, dog or moulds (called an allergen). In people sensitive to these allergens, exposure causes the release of chemicals from cells in the nasal passages, eyes or airways. This results in inflammation and irritation to the lining of the eyes, nose and throat.
Grass pollen is the most common allergen, which affects sufferers at the specific times of the year when grass pollen is released (May-July). However, some people become allergic to tree or weed and shrub pollens, and will therefore be affected at different times of the year (February-June for trees; September and October for weeds). The patient who is allergic to tree, grass and weed pollens may suffer a very prolonged ‘hayfever’ season. Rhinitis which occurs for only part of the year in this way is called seasonal allergic rhinitis.
Symptoms that continue all year are called perennial allergic rhinitis and commonly relate to indoor allergens, such as house dust mites, pets and indoor moulds.
Allergic eye (Allergic conjunctivitis)
Many people suffer the symptoms of allergic conjunctivitis, either seasonally (seasonal allergic conjunctivitis) or all year round (perennial allergic conjunctivitis). The main symptoms are itching, burning, watering and redness of the eye, and puffiness of the eyelids.
Asthma is the term which describes a specific type of breathing problem that arises due to narrowing of the airways. This narrowing is caused when certain natural chemicals within the body are released, usually in response to infection or when the patient comes into contact with something that they are allergic to. The same release of chemicals also leads to inflammation of the airways.