Patch testing

Patch testing is a procedure used to determine if your dermatitis / eczema / rash is caused by a contact allergen (e.g. nickel, dyes, perfumes, preservatives). Patch testing is different from skin prick testing, which is used to diagnose environmental allergies that affect the nose, eyes and airways (e.g. cat dander, grass pollen, dust mites, etc.) and immediate type food allergies. Like any type of test in medicine, there can be false positives and false negative test results.

 

If it is determined that you have a contact allergy, then we will provide avoidance sheets as well as a list of products that are free of your contact allergens using the ACDS CAMP database. A free app for your phone (ACDS app) can then be used to search for products.

The appointments:

The first appointment will take 30 minutes. The patches with allergens will be applied on the back. Tape will be placed over the patches to keep them in place.

The second appointment will occur ~48 hours after the first appointment. The patches are removed, and the allergen sites are read for evidence of reaction. Permanent marker will be used to outline the patches.

The third appointment is 2-3 days after the second appointment. The allergens are read a final time.

• Do not expose your back to the sun for 4 weeks before your patch testing
• Wear old clothing as marker can stain clothes
• Do not swim, rub, or exercise as the patches may come off
• Keep the back dry, so no baths, showers or unnecessary sweating while the patches are in place
• Arrange for someone to remark the test sites with indelible felt tip marker between the 2^nd and 3^rdreadings

Preparing for patch testing:

1. Shower the morning of the test
2. Do not put creams or oils on your back the morning of testing
3. If there is hair on the back where the patches will be applied, shave (electric razor is preferable) a day or two before testing (do not use chemical hair removal products)

In very rare cases, patch testing can lead to sensitization to a contact allergen