An Allergy is a hypersensitivity to foreign substances which are normally harmless but which produce a violent reaction in the allergy sufferer. Allergies are generally the body's effort to eliminate something it considers unsuitable. Typical allergic reactions are
hay fever, migraine,
asthma,
allergic rhinitis,
digestive disturbances,
coeliac disease,
conjunctivitis,
urticaria,
eczema,
drowsiness,
CFS,
hyperactivity in children,
tinnitus, recurrent sinusitis and
ear infections.
In a few people the histamine (anaphylactic) reaction can cause muscle cramps, disorientation, unconsciousness and death from shock or suffocation.
There are different types of Allergies, the most common being type1.
When an allergen encounters cells capable of antibody formation, they then form IgE antibodies which bind to the surface of other cells, called mast cells and basophils. In response to the attachment those cells release chemicals, called mediators of anaphylaxis, among them histamine. Those chemicals cause allergic reactions such as swelling or the secretion of mucus.
Almost any substance can be an allergen for an individual. Common allergens include certain foods, especially milk, wheat and eggs, pollens, dust, moulds, cosmetica and certain
food additives.
An Allergy is not the same as an intolerance. Allergies always involve the immune system, whereas an intolerance, eg. lactose intolerance, is caused by a lack of lactase, the enzyme that converts lactose into glucose.
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