Allergy testing

All extracts are sourced from Bio-Diagnostics (UK) and US allergy company Greer Laboratories. If you wish to read how the extracts are created then check the websites.

What we test for on the day will depend on the condition, known sensitivities and previous reactions. The number of extracts used will vary from a minimum of 24 to a maximum of 48 (this may be extended to include a few specially selected allergens depending on the patient’s history).

If you or your doctor wishes you to be tested for something not on our list please contact us by e-mail ( For example if you bring a small sliver of fresh food, the leaf of a specific tree where sap can be squeezed out etc, then that can be tested directly. This is usually done for specific fish you suspect that you might have reacted to and we do not have it in allergy extract form.

DO NOT, UNDER ANY CIRCUMSTANCES, TURN UP WITH A SHOPPING TROLLEY FULL OF THINGS YOU WANT TO BE TESTED FOR (it has happened!). Everything must be cleared with the clinic by e-mail beforehand.

Interpretation of results

First of all each extract is discarded 4 weeks before expiry date to ensure concentration and potency does not wane.

A positive result is measured in mms of central wheal and outer flare (redness of skin). There are positive (histamine) and negative (saline) controls to compare against and thus ensure accuracy of test result.

With foods, a wheal of 6mms and greater suggests that food will trigger an allergic reaction. The greater the size of the wheal, the more likely that the reaction will be aggressive.

With inhalant allergens (such as dust mite, pollens, animal hair) the size of the wheal and flare is important but does not always reflect the symptoms. For example a patient will occasionally show a very large wheal and flare (say to dust mites) but not show many symptoms. Equally a relatively small reaction (say to cat hair) in someone only recently exposed to cats is usually very important as within a year of continuous exposure the allergic reaction will probably have increased significantly (as will the patient’s symptoms).

It’s easy to perform an allergy test, the skill lies in interpreting the result and linking it to the patient’s symptoms. Often there is no link.

All reactions will be recorded in mms of wheal size with surrounding flare measured separately and recorded.