Allergy Testing, What Does It All Mean?

Those who have been through the allergy diagnosis process will know that it can be somewhat complex. There are a variety of different testing methods for IGE (fast if not instant reactions) allergies. All of which require a referral from a GP. For those just getting to grips with allergies it can all seem very overwhelming. Here I discuss the different test’s available, what they entail and what it all means.

Skin prick testing – Probably the most common type of testing for allergies, skin prick testing involves dropping a solution, for example milk, onto the skin. The skin under the drop is then pricked with a needle and if you are allergic to the solution dropped, a raised, red, and sometimes itchy bump will appear. Usually within 15 minutes. Skin prick testing is fairly quick and simple and causes little to no discomfort for the patient. It is important to remember to stop taking anti-histamines 72 hours before testing to be sure that the test results are reliable.

Blood tests (RAST) – A radioallergosorbent test (RAST) is a blood test using radioimmunoassay test to detect IgE antibodies. A sample of blood is taken and tested, the results are usually available 7-10 days later.

Patch tests – Patch testing is a form of testing used to investigate contact dermatitis. Contact dermatitis is a form of eczema caused by your skin coming into contact with an allergen. A small amount of suspected allergen is placed on a metal disc which is then placed onto the skin using tape for 48 hours to monitor for a reaction.

Food challenges – This form of allergy testing is one I fear the most. Thankfully I am yet to go through this with Theo. Food challenges usually take place in hospital. An allergen is fed to the patient in small amounts to see how the patient reacts. This is done under close supervision in case of a severe reaction.

Elimination diet – Do you suffer from delayed reactions? Bloating, diarrhoea and eczema are all symptoms of a delayed reaction. An elimination diet is the best way to figure out whether an allergen is the cause. If, once the suspected allergen is removed from the diet, the symptoms improve or even disappear, then it is advised you continue to exclude the allergen for at least six months before attempting to consume again.

Over the last 4 years I have dealt with Theo’s allergies and observed as he has undergone many of the tests listed above. If you have any question’s or worries you wish to discuss confidentially with someone who has experienced it all, please feel free to email me at

For more information on allergies and allergy testing please visit the Allergy UK website. Find out more about the difference between allergies and intolerance here.