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Patch Testing

Red, hot itchy skin rashes can be caused by allergens that contact the skin. These skin allergy triggers can be very hard to figure out. If you or your child is experiencing rashes Sandra A. Ho, MD at Avant Allergy in Los Angeles, California can conduct patch testing to identify compounds in everyday items that may lead to rashes.

How is patch testing done?

Common known allergenic compounds are placed on the skin of the back and left on for 2 days. During that time you will not be able to shower or exercise vigorously. The patches are then removed after 48 hours and the test is read by Dr. Ho. You will then come back on another day for a final read as some reactions take more than 48 hours to appear.


What sorts of compounds are tested?

  • Metals

  • Medications

  • Fragrance

  • Preservatives

  • Sunscreen components


Who should get patch testing?

Those with a history of skin rashes or eczema should get patch testing to evaluate what contact allergens may be contributing to these rashes.


Is patch testing the same as skin prick testing?

Skin prick testing looks for immediate reactions to dust, pollen, mold and animal dander while patch testing looks for delayed skin reactions to chemical agents contacting the skin.


If you are struggling with skin rashes and want to find out what may be causing them, Sandra A. Ho, MD will be able to use patch testing to identify triggers. Make an appointment today online or call Avant Allergy in Los Angeles to schedule an appointment.

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