Patch Testing

What is Patch Testing?

Patch testing is a simple procedure to help diagnose allergic contact dermatitis and identify the causative agent(s). This involves the application of a series of purified ingredients to your back in small amounts as test patches.

For more information on patch testing visit dermnetnz.org

We test using an extended battery of allergens.

Prior to your appointment

  • If your back is hairy please shave or wax one or two days before patch testing.
  • Do NOT take cortisone (prednisolone 10mg or less a day is usually okay) tablets before or during patch testing, without checking with the doctor.
  • Do NOT use creams (including topical corticosteroids / ‘cortisone’ creams) or powders on your back the day the patches are applied.

For your first appointment

  • Bring in all the creams you have been using. This includes face creams, moisturisers, sunscreens and medicated creams. Testing might be done to some of these.

While you have patches

  • Unless otherwise directed, leave the patch in place until it is removed in the doctor’s office. Patches are usually removed after 48 hours.
  • In order to prevent falsely negative test results, you should not bath, shower or wash your back or have excessive sunlight or sunburn anywhere on your body during the entire test period.
  • Please try to avoid physical activities that could make you sweat as well as movements that could cause the patches to come loose.
  • If a patch should at some time loosen, please fasten it with additional adhesive tape (such as micropore from your local chemist) in exactly the same place and inform the clinic.
  • If you should feel some itching (this sometimes occurs when the test is positive), please do not scratch. You may apply cold packs to decrease the itch and/ or take antihistamines (e.g. Claratyne, Zyrtec or Telfast 10mg during the day, [non-drowsy]) without adversely affecting the result.
  • Please visit the clinic at the scheduled dates for the monitoring of your test results. As a rule this will be Monday, Wednesday and Friday – please understand that this is necessary.
  • At the time of the first reading the patches will be removed. Please remember that you still should not wash or expose the tested sites to sunshine until after the final reading. Final reading is usually performed another 48 hours after the patches have been removed.
  • Time off work may be required and a certificate will be available.

After the test

If you are shown to be allergic to any of the substances tested, you will be given comprehensive information and advice on how to avoid this allergen. If you have any problems or concerns please contact the clinic or surgery.

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