Allergies are caused by exposure to airborne allergens; as a result, the lining of the nasal cavity becomes irritated and inflamed. Allergies are not contagious. The symptoms only vary a little from the common cold. They include sneezing, watery eyes, coughing, itchiness in the nose and throat, postnasal drip that stays clear, and perhaps a dull headache.
High temperature and an achy body are not indicative of allergies. The symptoms last longer than a week and may be year-round depending on the allergen. Numerous allergens may cause symptoms of seasonal allergies: pollens are most common in the spring and fall. Allergens such as dust mites, animal dander from pets, moulds, fungi and cockroaches may produce year-round symptoms.
An allergy is an abnormal reaction to ordinarily harmless substances. These substances, called allergens, may be inhaled, swallowed or come into contact with the skin. When an allergen is absorbed into the body it triggers white blood cells to produce IgE antibodies. These antibodies attach themselves to mast cells causing the release of potent chemical mediators such as histamine, causing typical allergic symptoms.
Some common allergens are:
- mould spores,
- dust mites,
- animal dander,
- insect stings.