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Patch Testing

What is patch testing?

Patch testing can help determine sensitivities to common environmental exposures (such as fragrance, nickel, metals contained in knee and hip implants, cosmetics, chemicals, etc.) which may lead to a rash (contact dermatitis). Contact dermatitis is typically a delayed reaction to contact with an allergen.

Symptoms may take 24 – 72 hours to appear and may include redness, itching, soreness and vesicles or blisters. The patch testing can help to identify potential allergens that can be avoided.

How does patch testing work?

A panel of patches with many common allergens is placed in contact with the skin on the upper back and covered with adhesive. These patches are worn for 48 hours and removed in the office. Initial impressions are recorded in your chart. You will return for a final reading of the patches 48 – 96 hours later. This last visit will help distinguish between irritant dermatitis (which is not a true allergic response) and contact dermatitis. Information on any positive responses will be provided so that these substances can be avoided.

Instructions for Patch Testing Appointment

  1. No corticosteroids (oral, topical, or injectable) for 1 week prior to the patch test or during the week of the test.
  2. No Elidel (pimecrolimus), Protopic (tacrolimus), cyclosporine, Imuran (azathioprine) or CellCept (MMf) 1 week prior to the patch test or during the week of the test.
  3. No topical antihistamine for 1 week prior to the patch test or during the week of test. Oral antihistamines may be taken.
  4. No UV exposure or tanning beds for 3 weeks prior to the patch test or during the week of the test.
  5. Do not wash the patch test area until after the final reading is completed (one week after application).
patch testing example

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