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. In some, peanuts cause such a reaction.

There are different types of allergies. The most common is 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.

These chemicals cause allergic reactions such as swelling or the secretion of mucus. Almost any substance can be an allergen for an individual. Some people have intolerance for foods like milk, wheat and eggs; others have an allergic reaction to pollens, dust, moulds, cosmetics 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.

Overactive and hyperactive children, epileptics and mentally ill adults, aspirin sensitive persons and those with chronic skin rashes, migraine sufferers may find the following list a guide: