Patch testing is a medical procedure (the most reliable way) used to identify the substance that is causing your allergic contact dermatitis. This procedure puts small amounts of common substances on a series of patches on the back. At least 60 patches are usually tested at once.

After removing the patches, the dermatologist checks for any reactions, such as red areas. If you test positive for any reaction, the dermatologist will provide you written information on how to avoid the allergen(s). Simply completely avoiding the allergen(s) may cause the dermatitis to subside.

Dermatologists are certified to perform patch testing. In Melbourne, only a few clinics offer patch testing because of the requirements to stock the allergens and trained nursing staff required. Patch testing is available at Kew Dermatology, public dermatology clinics and the Skin and Cancer Foundation.

Patch testing takes one week to complete. The patches are placed on a Monday and then removed the following Wednesday. A final reading is done that Friday.

Standard testing is $520, which includes the three appointments, the patches and equipment used, and handouts detailing how to avoid the allergens you reacted to.
Extra allergens (to be specially ordered) are charged at cost price.

A referral from your general practitioner entitles you to claim from Medicare about half of the total cost. With a Medicare referral, you will spend about $300 out of pocket.

If you need your dermatitis investigated, you need a referral from your general practitioner and have to first consult with us about what you need to be tested for. An initial consultation is necessary because some chemicals are specific to certain occupations (e.g., bakers, carpenters, dentists, hairdressers) and have to be ordered (some even imported from Germany) before the test. We will also ask you to bring some of the products you use at home, such as your facial cleanser and moisturiser, sunscreen, shampoo and shower gel. In this visit, we will explain the procedure, schedule the testing sessions and quote you the full cost.

Further, you should plan your week around the test as the patches cannot get wet. This means you have to temporarily avoid excessive sweating (e.g., from exercise) and change how you wash. We suggest washing your hair that Monday morning before going to the clinic (i.e., before your first session), and using dry shampoo if needed.
You can also wash your hair over a sink to avoid wetting the patches.

Also note that we can’t proceed with the testing if you have a rash on your back or are taking certain medications.

Prick testing checks for substances that cause hives, hay fever and food allergies. It can be performed—often on the arm—on the spot by an immunologist. By contrast, patch testing checks for substances that cause longer-lasting rash, takes longer to conduct and is done on the back and by a dermatologist. Visit avidallergy.com.au for more information.