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Contact Allergy Testing

Contact Allergy Testing

Patch testing is a procedure to identify if a particular substance or chemical may be causing your rash. Patch testing is used to identify substances which may be causing an allergic contact dermatitis.

Allergic contact dermatitis often presents as a type of dry and scaly rash. If you notice a particular flare up using certain products such as cosmetics or fragrance, your contact allergy may be the cause of your dermatitis.

Contact allergy may also be the cause of dermatitis around the eyes, or dermatitis which flares up very suddenly.  Some patients may have long standing eczema since childhood which is aggravated later in life by a contact allergy.

The patch testing process involves using small amounts of chemicals that we are commonly exposed to and placing these onto a series of “patches” on the back. At least 60 patches are usually tested at once. The patches are applied on a Monday, and the test is read after it is removed on Wednesday and Friday the same week.

After removing the patches, the dermatologist reads your test and identifies any red areas that have reacted. If you have positive reactions, you will then be given written information on how to avoid these substances.

Some of the more common reactions that we see in the clinic include;

  • Preservatives used in cosmetics and shampoo
  • Fragrance
  • Nickel allergy (which may cause reactions to jewellery)
  • Sunscreen allergies
  • Rubber (used in gloves)
  • Some topical medications

If you think you would benefit from patch testing to investigate your dermatitis, you will need to see the dermatologist first to discuss what you may need to be tested for. Certain professions come in to contact with particular chemicals which may need to be ordered in advance e.g. dentists, hairdressers, bakers and carpenters.  We will also discuss whether you need to bring any of your products from home to be tested, such as your facial moisturiser or cleanser.

Please also view our Patch Testing & Skin Allergies page. After your initial visit a suitable time for patch testing will be organised and the full costs quoted prior to starting the testing process.

A referral from your GP will usually allow you to claim approximately half of the costs back from medicare.

Please have a look at our FAQs below and you can find further information on skin patch testing at Melbourne City Dermatology here:

Contact Allergy FAQs

Your questions answered

How is patch testing different from prick testing?

Patch testing will help to determine the cause of an allergic rash. It will usually identify substances which contact the skin and cause an itchy red rash that can last for days/months or even years! The patch procedure takes a week to perform correctly and is usually applied to the back by a dermatologist.

Prick testing is a much faster procedure which looks for substances that cause hives, hayfever and food allergies. If you think that you need prick testing, then we recommend discussing with your GP if you need to see an immunologist. Prick testing can be performed “on the spot” with an immunologist and is usually tested on the arm at the time of your appointment.

How long does patch testing take?

It takes a week to complete a patch test. Your patches are applied on a Monday, then removed on a Wednesday. We ask you to return for a final reading of the test on Friday.

After this appointment you will have your results and information provided about any positive reactions.

Does Medicare cover patch testing?

Patch testing involves a significant amount of time and expertise as well as allergens which need to be imported from Germany. Unfortunately, Medicare will only cover a portion of the fees for patch testing.

Providing you have a medicare referral, you will be approximately $300 out of pocket for the patch testing process. This includes the 3 clinic visits,  testing to 60 standard allergens, and your own skincare products when relevant.