What is patch testing?
Patch testing is a test used to identify particular agents which cause allergic contact dermatitis.
What is allergic contact dermatitis?
Allergic contact dermatitis is a skin condition which develops because of an allergic reaction from various substances found in every day products such as soaps, shampoos, detergents, cosmetics, perfumes, and lotions. Some people are allergic to ingredients in medicated products such as steroid or antibacterial ointments. Metals in jewelry such as nickel or gold, and latex or rubber in shoes or gloves, can also result in allergic contact dermatitis. Individuals with allergic contact dermatitis can develop rashes, itching, and blisters with exposure to ingredients in these products. These rashes are usually treated with steroid creams or ointments, but often time the benefits are short lasting. The most effective method to treat allergic contact dermatitis is to identify the specific substances which cause the reactions.
How can a patch test help me?
A patch test is designed to help identify the particular ingredients or items that one is allergic to. This could include an ingredient in a soap or detergent, or in a cream, a metal used for an implant.
Not all patch tests are alike. Some doctors only offer patch tests containing only 28-35 items. Unfortunately, these limited patch test panels can often miss many allergens which cause allergic contact dermatitis.
Dr. Dauby offers a more comprehensive panel of over 80 items, dramatically increasing the chance of catching the cause(s) of contact dermatitis. Dr. Dauby also performs a metal implant patch test panel specifically designed for patients with metal sensitivities who may require an implant for an orthopedic surgery or insertion of a medical device.
What should I expect with patch testing?
Patch testing consists of 3 appointments over a week's time.
Appointment 1: Monday. At this appointment, we will apply the patch tests on your back. The substances to be tested for will be applied to your back in special small containers and/or chambers held within a tape and labeled with ink. This appointment may take up to 1 hour. The substances remain taped on your back until your next visit.
Appointment 2: Wednesday. At this time, the patches are removed and your back will be examined for any reaction. This appointment may take up to 1 hour.
Appointment 3: Thursday. We perform a second examination of your back to evaluate for positive results. At this time we will provide you with information on which items you are sensitive to and how to avoid them.
Preparing for patch testing:
You should not take any oral steroids ( prednisone or solumedrol) for at least 2 weeks before application of patch testing, and the week of patch testing. There is no need to stop anti-histamines, singulair (montelukast), or asthma inhalers for patch testing. Do not expose your back to the sun or sunbed for at least 2 weeks before the patch testing.Wear old, dark clothing as pen marks can stain clothes.Shower the morning of the test, as you cannot get your back wet from the time the patches are applied to the time of the second reading.Do not put any creams or oils on your back the morning of the testing.If there is hair on the back where the patches will be applied, shave (an electric razor is preferable) a day or two before testing (do not use chemical hair removal products).After the patch test has been placed:Do not swim, rub, or exercise, as the patches may come off. Minimize sweating, excessive physical activity, or playing sports during testing.Keep the back dry, so no baths, showers, or unnecessary sweating.Do not expose your back to sunlight during the testing.Try to sleep on your side or stomach. Try to wear a T-shirt to bed. You may continue to use any prescription creams you have been given for your rash anywhere on your body EXCEPT your back. DO NOT apply any creams or ointments to your back. You may take benadryl or other antihistamines for itching but do not take any oral steroids.Avoid sun exposure and tanning beds 2 weeks before and after patch testingIf the patches are extremely itchy painful or burning, please call our office if you are concerned.If a patch starts to peel off, reinforce with tape such as Micropore or Scanpor. If a whole patch comes loose, remove it and note the time and date.
What are the side effects of patch testing?
Skin reddening and itching at the application site (a positive test result)—this usually disappears after a few days. A strongly positive reaction could cause a blister.Persistent reaction—some positive test reactions, for example, to gold, may persist for up to a month.Flare of eczema—a positive PT may be accompanied by a flare of existing or previous eczema.Pigment change—an increase or decrease in pigment may be seen at the site of patch tests this may last for months or rarely (1 in 1000) is permanent.Infection—this is rare and would need antibiotic treatment.Scarring—very rare (1 in 10,000).Allergy—rarely, in approximately 1 in 5000 patch tests, you may become allergic to one of the substances applied during patch testing. In practice, this does not seem to cause problems in the long term.
NOTICE: Patch test supplies are very expensive and take a lot of preparation time for the staff. If for some reason you need to cancel your appointment, you must notify us no later than the Wednesday preceding your test date, or you will be charged a $50 cancellation fee.
