An allergy means that a person’s immune system shows an excessive defence reaction to substances which in themselves are harmless – it has “forgotten” how to distinguish between harmful and harmless substances.

The symptoms of an allergic reaction vary considerably. The most frequent complaints occur shortly after eating, either in the form of prickling or swelling in the mouth or throat, or as a skin rash.

Allergic reactions in the gastro-intestinal tract, such as nausea, vomiting, diarrhoea or constipation, occur in relatively few cases.

More seldom still are shock reactions (anaphylactic shock). These can bring about circulatory failure, which must be treated immediately by a doctor.

A food allergy is one thing – a food intolerance is another. A food intolerance can produce symptoms very much like those of food allergy, but the immune system is not involved in these reactions in the same way. If you have a food intolerance, your body is unable to digest a certain kind of food or some ingredient in a food, e.g. because the required enzyme is absent or inactive.

Since the digestive system is involved in most cases, the principal symptoms of food intolerance (such as lactose intolerance – link to the same topic) are flatulence, gastro-intestinal pains and diarrhoea. Allergies and food intolerances can appear in many different degrees of severity.

Under certain circumstances it is urgently advisable to consult a doctor specialised in allergology, who will be able to determine the exact causes and draw up an individual diet plan together with a dietitian.