Allergies occur when the immune system in some people becomes sensitive to common and usually harmless substances like pollen, dust mites, and moulds . These substances are called ‘allergens’.
Pet dander (loose skin flakes) may also cause allergic reactions.
What you feel are the effects of histamine and other powerful chemicals your body releases when allergens come into contact with your own allergen-specific antibodies. The actual symptoms experienced can include hayfever and skin reactions such as hives.
Indoors and out
Allergens are almost everywhere – both indoors and outdoors – and in some cases identifying the cause of a specific allergic reaction is obvious. But at other times, doctors have to carry out a series of tests to isolate the cause of a problem.