Patch Testing

What is the reason for a patch test?

Patch Testing is a diagnostic method used by healthcare professionals to identify a Type IV Hypersensitivity or Type IV allergy, sometimes referred to as Allergic Contact Dermatitis. Type IV allergy tends to be associated with workplace allergens such as the chemicals used in hair salons, cosmetic products, and other small molecular weight chemicals.

What will happen during and after the patch test?

Your healthcare provider will use a TRUE TEST patch testing kit to pinpoint the allergen causing your reactions they may also highlight other allergens that you did not realise you were allergic to. The patch test will be placed on your back, so make sure this area is accessible by wearing a loose-fitting top where possible. Make sure your back is clean and free from oils such as moisturisers. Your healthcare provider will then stick three patches to your back containing 35 potential allergens.  They will also use a pen to mark your back.  This helps the results to be read later.

Your healthcare professional may add a covering panel which will hold the test in place and will allow you to shower, although bathing is not advised. Speak to your patch tester to see if this protective panel has been used, if not you will need to refrain from showering. Try to avoid sweating and continue to wear loose-fitting clothing if possible. Do not sunbathe or use a UV sunbed whilst you have the patches on or afterwards.  You will also need to refrain from taking any medication containing steroids.  If you are prescribed steroid medication you must discuss this with your healthcare professional.

After 2 days the patch test will be removed.  At this point you will be able to take a shower but try to avoid touching/rubbing/soaking the test area.

The results will be read by your healthcare professional a further 2-3 days after the patches have been removed.

Will the patch test be painful?

The patches are stuck on with a hypoallergenic glue.  The application of the skin patch tests will not be painful.  You may notice some itching or discomfort after a few hours or days – this is usually suggestive of a positive reaction.  If you do find yourself itching try not to scratch as this can impact the results.  You may also notice some small rashes on your back once the test has been removed.  Your healthcare professional will look at these rashes to ascertain if you are allergic to a substance.

Is the test 100% accurate?

The patch test will be used alongside a clinical history – this will involves asking you some questions about things you may regularly come into contact with.  Some medications may give a false result, so it is important you discuss and medicine you take with your healthcare provider.

What if the test shows I am allergic to something?

You can discuss potential treatments and method to avoid these things with your healthcare practitioner. There are a few products on the market that may be able to assist.