Advice to Patients
- There should be no rash (eczema/dermatitis) on your back & upper arms the day the patches are applied to your skin (Visit #1).
- No sun exposure, tanning or UVB phototherapy to your back & upper arms for at least 1 month before patch testing.
- The patches must adhere to the skin and remain in place for 48 hours. For men, it is recommended that the test area be trimmed of any hair growth 2-3 days prior to your first visit.
- Do not apply moisturizer or prescription creams to the test area the before and during patch testing.
- You should not get your back wet after the patch tests are applied to the skin.
- Avoid excessive exercise which causes heavy sweating or patches to loosen.
- Avoid friction or rubbing the patch tests, as this may cause them to come loose.
- The patches are outlined with dark ink prior to removal – please wear dark colored clothing to reduce the risk of staining.
- Should the patch or adhesive tape become loose, apply additional adhesive tape to the patch so that it is again fixed to the skin.
- Antihistamines can be used if the patch test sites become itchy.
- If you observe a late reaction to a patch test site (three or more weeks after testing), you should report this to your dermatologist.
Possible adverse reactions when being patch tested
- Your dermatitis may “wake up” if you have a positive reaction to the allergen that caused it.
- Uncommonly, a reaction may persist for a few weeks. It can be treated with cortisone cream.
- As they heal, positive reactions may sometimes leave brown or white spots on the skin. Most of these marks will fade slowly over time, but some may be permanent. True scarring is rare.
- Very rarely, people may develop an allergy to a substance used in the tests. This usually presents as a positive patch test reaction 2-3 weeks after the patches were applied to the skin.
Here are some helpful sites with important information about contact dermatitis and patch testing. We encourage our patients to review as much as they can before their appointment.
- American Contact Dermatitis Society
- Contact Dermatitis Institute
- American Academy of Dermatology
- Canadian Dermatology Association
- DermNet New Zealand