Allergy Diagnosis 

What is an Allergy?

An allergy is an abnormal immune reaction to otherwise harmless substances such as pollens or foods. It is caused be the development of an IgE antibody,  the reaction is usually immediate and may vary from mild to very severe.


What you tell us is the most important aspect of diagnosis and therefore an allergy focused history will always be taken by the doctor or nurse who sees you. Different types of testing may also be required:

  • Skin prick testing (see picture) is simple, safe and provides results within 15-20mins. The skin prick test introduces a tiny amount of allergen into the skin, eliciting a small, localised allergic response, in the form of a wheal (bump) and flare (redness). These tests can be carried out on all age groups. SPT is usually carried out on the inner forearm, but may also be carried out on another part of the body, such as the back or thigh. 
  • A blood test can also to used to aid/support diagnosis. A small blood sample is taken and sent to the laboratory to look for specific IgE to the suspected allergen. The results of such tests may take several weeks.
  • An allergy challenge test may also be undertaken to a food or drug if the results of testing are inconclusive or if it is suspected that a person is no longer allergic. When necessary, challenge testing is undertaken in our day ward where there are full resuscitative facilities


Immunotherapy is the process of changing a person's allergic status by administering small regular amount of the substance to which they are allergic, usually over a period of three years. Currently we have an active programme of grass pollen desensitisation, which is initiated in the department, but then continued by patients taking a daily tablet at home.  Pollen immunotherapy is not started during the pollen season and these clinics only run during the months of December – February.