What is an allergy?

An allergy can be triggered if your immune system reacts to substances (called allergens) that are harmless for most people.

You can have an allergic reaction to many different substances (known as triggers), including:

• medicines
• substances in our environment such as pollens
• foods such as eggs, seafood or nuts

What is an allergic reaction?

An allergic reaction usually happens straight after you have been exposed to a trigger and may cause a range of symptoms including:

• runny nose and watery eyes
• abdominal pain, nausea or vomiting
• skin rash

Most allergic reactions are mild, but some people experience a severe reaction called anaphylaxis. Anaphylaxis may cause breathing difficulties and low blood pressure that leads to collapse (when you fall down for no obvious reason, for example, fainting). This is a medical emergency and needs immediate treatment with adrenaline.

Read about how to use an adrenaline autoinjector.

Allergies may also trigger other medical conditions for some people, such as:

• asthma
• hay fever
• skin conditionssuch as eczema or urticaria (hives)
• eye conditions such as conjunctivitis

What is allergy testing?

If you have had symptoms of an allergic reaction in the past, allergy testing can help you and your doctor identify what you are allergic to, and what your triggers are. Testing can help your doctor advise you on the best ways to avoid these allergens.

What types of allergy tests are available?

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

Skin prick testing

During skin prick testing, a tiny amount of the allergen will be dropped onto the skin of your back or arm. Your doctor will then prick your back or arm with a small needle to expose your body to the allergen. If your body reacts to the allergen, the area where you were pricked will become red, swollen and itchy.

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 if you are allergic to this allergen.

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. If you are very uncomfortable, you may be able to take an antihistamine or pain-reliever medicine after the test to help get rid of symptoms.

You should avoid taking antihistamine medicines for a few days before skin testing, as they can interfere with the results. Your doctor may also advise you to avoid using creams or lotions on the area of skin to be used for testing.

Blood tests

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

Other tests

Other less common allergy tests include:

• intradermal skin testing
• patch testing
• oral allergen testing

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

ASK YOUR DOCTOR — Preparing for an appointment? Use the Question Builder for general tips on what to ask your GP or specialist.

Who should have allergy testing?

You may benefit from allergy testing if you suffer from asthma or hay fever, or if you have a reaction to insect stings or certain foods.

Testing can detect allergies to many types of allergens including:

• dust mites
• animal dander
• mould spores
• pollens
• certain foods
• some insect stings
• some chemicals and medicines

Who should perform allergy testing?

It is important that allergy tests are carried out and interpreted by trained health professionals. Your doctor may refer you to a specialist immunologist or allergist if a more complicated assessment is needed. It is important that the results of allergy tests are interpreted alongside your medical history. A positive test does not always mean you have an allergy.

Some alternative practitioners offer allergy tests and treatments. These tests are often expensive and may be of little or no use in correctly detecting allergies.

How much does allergy testing cost?

Medicare card holders will receive a Medicare rebate for part of the cost of allergy tests, if they have been ordered by a doctor. Concession card holders might receive a higher rebate.

In most cases, there will be some out-of-pocket costs, so ask about fees and charges when you book your appointment.

Why is allergy testing important?

Allergies may be dangerous and potentially life threatening. However, incorrectly assuming that you or your child have an allergy without proper evidence can lead to anxiety, unnecessary restrictions or even malnutrition. Some evidence even suggests that avoiding foods that your child is not allergic to may increase their risk of developing an allergy. Check with your doctor before you remove foods from your diet, or exclude foods from your child’s diet.

Resources and support

• More information is available on the Australasian Society of Clinical Immunology and Allergy (ASCIA) website.
• Allergy & Anaphylaxis Australia provide updates and advice for people with allergies.