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Introduction Patch Testing

Allergy refers to the hypersensitive reaction by the body’s immune system to any substance (metals, chemicals, dust, pollen, etc.). Dermatologists perform skin tests called Patch Testing to help identify the allergen (substance that causes allergy) and help treat the allergy. These tests are usually performed by application of a tiny amount of allergen onto the skin.

Testing procedure

If it’s your first visit, your dermatologist will take a complete medical history, discuss with you about your skin problems, and conduct a thorough skin examination. During the procedure, a very tiny amount of 60 different allergens are applied as a small patch or disc onto areas of normal skin, usually on the upper back, with the help of a non-allergic tape. These are fixed firmly and allowed to stay in place for 48 hours. In the course of time, you are not permitted to wash the area, expose the area to sunlight, or indulge in activity that might cause sweating. The nurse will remove the patches after 2 days and a doctor will review you again after 4days to examine the area and interpret the results. Based on the test results (negative and positive), your doctor will discuss the results especially if the results are positive, which allergens and products to avoid. Treatment will also be discussed. Doubtful reactions may require additional tests to help confirm the presence of an allergy.


The advantages of patch testing include:

  • Identify the cause of the allergy
  • You can go to work wearing the patch


  • Inability to wash your back for 3 days
  • Rarely severe allergic, irritant or burnlike reaction from contact with diluted allergen