Patch Testing

Patch tests are often used to determine whether a person has an allergy to substances in the external environment. The method our Skin Test Laboratory uses is the T.R.U.E. TEST® system.  The patches remain in place for a minimum of 48 hours. If you are allergic to one of the substances tested you will develop signs of skin irritation (redness, itching, and sometimes blistering) in the area where the material was applied.  The test areas have been marked with a marking pen so that the location of each test is known.  Do not remove the markings.

Recommendations for Patch Test Care:

  • Please stop taking all antihistimines 5 days prior to application.  Ie: Allegra, Benadryl, Clarinex, Singulair, Atarax, Nasonex or any type of anti-itch/seasonal allergy medications.  Do not apply any type of ant-itch creams or lotions.
  • Keep the entire patch area dry until the patch is removed.  Once it is removed you may shower, but do not scrub your back; just allow water to run over your back.
  • Do not engage in strenuous activity while the test is in progress.  Any activity in which considerable sweating occurs should be avoided, as this may cause the tape to loosen.
  • At bedtime, it is preferable to wear a t-shirt to avoid catching the edges of the tape on the bed sheets.
  • A positive test will itch.  Please refrain from scratching your back, since this may affect our interpretation.
  • If any patch test site itches or burns severely remove it at once and notify our office.  There will, of course, be a little mild discomfort or itching associated with having tape on your skin or positive reaction.
  • A positive test reaction may take several weeks to subside.

Patch Testing Schedule

  • Monday : Patch test application in our office
  • Wednesday : Remove the patch test yourself, at home
  • Friday : You will come into office to have the results read

External Links:
For more detailed information, please refer to the American Academy of Dermatology.