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Patch Testing

Patch Test Instructions

Patch testing is a test to assess your skin’s reaction to a variety of substances which you may encounter in your home, at work, or during recreational activities.  The tests consist of chemicals (allergens) which will be placed on adhesive strips on your back.  There are no needles or “pricking” instruments used in this form of allergy testing.

Patches will be placed on Day #1 at The Bellevue Laser and Cosmetic Center.  At that time, you should bring with you all products that you suspect you may be reacting to, as well as any products that Dr. Chiu has requested.  It is important that we have a list of ingredients contained in your products – this list can be found on the item itself or on its packaging.  Patches will be removed on Day #3 and the final read will be done in the office on Day #5.

1.  Patch sites will be marked with indelible ink and must remain dry.  Please keep the back and patch area dry for the entire 3 days until patches are removed.  A sponge bath except on the back area is preferred.

2.  Do not engage in strenuous activity while the test is in progress.  Any activity in which considerable sweating occurs or the patches may loosen should be avoided during the course of the testing.

3.  Avoid friction or rubbing of the patch tests as this may also cause them to become loose. Should the patch test or adhesive tape become loose, apply additional paper tape to the patch test so that it is re-attached to the original area.

4.  To avoid catching or tearing the edges of the tape or staining clothing or bedding, a dark colored T-shirt should be worn.  Please bring or wear a dark shirt to your appointment as the ink occasionally rubs off on clothing.

5.  There may be mild discomfort and itching associated with a positive reaction or due to the tape on the back.  Avoid scratching the areas where redness and itching appear as this can interfere with the results.  If you are itchy during testing you may take an antihistamine (diphenhydramine or Benadryl).

6.  Do not expose the test area to the sun or an ultraviolet lamp during testing and for at least one week prior to testing.


7.  Certain medications are not compatible with patch testing and may interfere with the results.  In order to obtain accurate patch test results, please stop taking any oral cortisone medications (prednisone) 2 weeks before patch testing is to begin.  We usually need to wait at least four weeks after a person has been given a cortisone (Kenalog) shot.  Also, do not use any topical creams or ointments on your back for 5 days preceding the patch testing.


8.  Occasionally patients have vigorous reactions to some substances.  This may result in local discomfort which can be treated at follow up appointments with cortisone cream or injections into the allergic site.  Also, some chemicals may temporarily stain the skin because of a brisk allergic reaction, or because the chemical dyes the skin.  These changes are usually temporary and will fade with time.


9.  Rarely, you may observe a reaction at the test site as late as 3 weeks after your visit .  If this happens, please report it as it may be important to your results.


10.  Your primary rash may worsen during the patch test procedure.  Patch testing does not guarantee a positive outcome or improvement in your rash.


Patch Test

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