What is allergy testing?

Allergy testing can be used to find the cause of allergy and asthma symptoms.

Knowing what you're allergic to can help you manage your allergies. This might be through avoiding or lowering your exposure to your triggers.

The most common types of allergy tests are skin prick tests and blood tests.

Skin prick testing

Skin prick testing is the easiest method of allergy testing. It involves a tiny amount of the allergen being put on your skin and pricked with a small needle. This exposes your body to the allergen.

If you react, your skin will develop a small itchy lump surrounded by a red flare.

Blood tests

Blood tests can also be used to test for allergies. They may be used when skin prick testing is not suitable. This might be if you have severe eczema or are taking medicines that may interfere with skin prick testing.

Other tests

Other allergy tests include:

• intradermal skin testing — for allergies to antibiotics, vaccines and insect venoms
• patch testing — for allergic contact dermatitis
• oral allergen testing — used to find the trigger of a severe allergic reaction

Your doctor can advise you on which allergy tests are most suitable in your situation.

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When is allergy testing needed?

You may benefit from allergy testing if you have:

• asthma
• allergic rhinitis (hay fever)
• an allergic reaction to insect stings
• an allergic reaction to certain foods

Allergy testing can detect reactions to many types of allergens (substances that cause allergies) including:

• house dust mites
• animal dander
• mould spores
• pollens from grasses, weeds and trees
• certain foods

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How to prepare for allergy testing?

Your doctor will tell you how to prepare for testing.

You should not take any antihistamine medicines for 3 to 7 days before skin prick testing.

You may also be asked not to use creams and moisturisers on your arms or back before skin prick testing.

You also need to be well in the 3 days before skin prick testing.

Where can I get allergy testing?

Allergy tests should only be carried out by trained healthcare professionals. They know how to:

• do the test
• select allergens
• interpret your results

It's important that the results of allergy tests are looked at along with your medical history. A positive test does not always mean you have an allergy.

Your doctor may refer you to an immunologist (a doctor who specialises in the immune system).

Medicare rebates will cover part of the cost of allergy tests, if your tests have been ordered by a doctor. In most cases, there will be some out-of-pocket costs. Ask about fees and charges when you book your appointment.

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What happens during allergy testing?

Skin prick testing

Skin prick testing is the easiest method of allergy testing. It's usually done on the skin of your back or arm.

Your skin will be cleaned with alcohol. A tiny amount of the allergen is put on your skin and pricked with a small needle. This exposes your body to the allergen.

If you react to an allergen, your skin will develop a small itchy lump, surrounded by a red flare. This happens after about 15 minutes.

After about 20 minutes, your doctor will measure the area of redness and swelling and record this measurement. Together with your medical history, this can help them understand which substances you are allergic to.

Although skin prick testing can be uncomfortable, most people find that they can get through it without too much trouble. Any swelling or itchiness will usually improve within 2 hours.

Patch testing

During a patch test, up to 30 substances may be tested on your skin (usually your back or arm). These substances can include:

• extracts from latex
• cosmetic perfumes and preservatives
• hair dyes
• metals
• plants
• foods
• glues and resins

Patches containing test substances are put on your skin and left for 48 hours. It's important to keep your skin dry during this time.

The test site will then be checked at different times. If you are sensitive to any of the allergens, you will get an eczema-like rash.

Are there any complications from allergy testing?

You may feel dizzy or light-headed after allergy testing and need to lie down.

You may be able to take an antihistamine or pain-relief medicine after the test to help get rid of symptoms.

Allergy testing can cause anaphylaxis (severe allergic reactions). This is very rare with asthma or hay fever.

Are there alternatives to allergy testing?

Some alternative practitioners offer allergy tests, such as:

• Bryan's or Alcat tests
• cytotoxic food testing
• electrodermal testing
• hair analysis
• kinesiology
• pulse testing
• reflexology
• vega testing (electro-diagnostic)

These tests are often expensive and can result in misdiagnosis. They are not recommended by the Australasian Society of Clinical Immunology and Allergy.

Resources and support

Learn more at the Australasian Society of Clinical Immunology and Allergy (ASCIA) website.

Allergy & Anaphylaxis Australia provide advice for people living with allergies. You can call them on 1300 728 000.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with you 24 hours a day, 7 days a week.