Diagnosis of allergy and allergy tests

Your doctor may:

• take a clinical history that includes information on what happened when you had a reaction to the allergen. They will ask whether you or anyone else in your family has any allergic disease.
• perform a physical examination. This may include looking at your skin, listening to your lungs and looking in your nose.
• order some tests.

Allergy testing can help find out which allergens cause your allergic asthma, allergic rhinitis (hay fever) and suspected allergic reactions to insects, foods, medications, or other allergens.

Evidence-based allergy testing

Doctors use test results, together with the patient’s clinical history (details of what happened when you encountered the allergen), to diagnose, recommend suitable treatment and management options, and tell you how to reduce exposure to allergens. Evidence-based allergy testing includes:

Skin prick tests or blood tests that measure allergen-specific Immunoglobulin E (IgE) antibodies:

• A positive skin prick test or blood test does not necessarily mean that a person is allergic to an allergen; it just means that they are sensitive to it or “sensitised.” For example, if someone has a positive skin prick test to egg but can eat egg with no reaction, they are sensitised to egg, but not allergic to egg. This is why testing should not be done unless the clinical history suggests there is an allergy.
• Many people with allergies focus on their skin prick test results. Having a larger welt does not mean the allergy is worse or that you will have a worse reaction. It tells doctors you will probably react if it is above a certain size welt, but how you react depends on many other factors.

Allergen challenge tests:

• Required for some people who have allergic reactions to food or drugs (medications) where a clear diagnosis is needed.
• The challenge tests are also done if someone is thought to no longer have their food or drug allergy.
• The most common challenge tests are oral challenges for food or medication.
• These tests must be performed under allergy specialist supervision in case of a medical emergency.
• For more information about oral food challenges click here.

Patch tests are used to test for allergic contact dermatitis.

Non-evidence-based tests

Non-evidence-based tests are expensive and can lead to unnecessary avoidance of certain foods and other potential allergens, such as grass or animals. They can also delay getting the correct diagnosis, proper treatment, and advice on managing allergies for you or your child.

Unproven methods of allergy testing are not recommended. They include cytotoxic food testing, kinesiology, hair analysis, vega testing (electro-diagnostic), electrodermal testing, pulse testing, reflexology, Bryan’s or Alcat tests, and Immunoglobulin G (IgG) testing for foods.

The Australasian Society of Clinical Immunology and Allergy (ASCIA) have a Frequently Asked Questions page to help you understand if the allergy testing you are having is evidence-based.