Sensitisation

Being sensitised means that the immune system has come into contact with an allergen; committed it to its memory; synthesised IgE antibodies against it and is ready to launch a defence reaction when the allergen reappears. The time it takes to become sensitised to an allergen varies from person to person (from a few days to several years). Until the IgE triggers the attack against the allergen, sensitised persons will have no symptoms when in contact with the allergen. Therefore sensitisation; which is the first step in developing allergy; occurs silently; without you knowing that it has happened. It is interesting to note that some people stop at this phase and never develop allergy symptoms even following long term exposure to allergens at high concentrations. These people have positive allergy tests but no evident allergic disease and therefore are considered to be healthy but at a higher risk for developing allergy than people who do not have any sensitisation.

The fact that positive IgE tests occur in individuals without clinical disease means that such tests should never be done in isolation but only as part of a consultation with someone who is trained in allergy.