Patch Testing

About Patch Testing:

+ What is allergic contact dermatitis?

Allergic contact dermatitis is a rash caused by direct contact with an allergenic substance.  The chemicals that cause this rash are referred to as allergens and can be an ingredient in your makeup, hair dye, fragrances, jewelry, topical medications, clothing, cleaning supplies, gloves, paint, shoes, etc.  Even small amounts of allergen can provoke allergic contact dermatitis in sensitive individuals.  Allergic contact dermatitis cannot be cured, but it can be controlled adequately if the culprit allergen is avoided.

+ What is the benefit of doing a patch test?

Patch testing is reliable, safe, and easy. It can help to determine if your rash is caused by a reaction to specific chemicals.  Identifying potential allergens and knowing which products to avoid will greatly improve your rash, although it may take several weeks.  If you have a positive test, we will teach you how to avoid your allergen and offer a list of “safe” products to use.

+ How does the patch test work?

It’s easy! On day 1 (Monday), the patches will be applied to your upper back – 80 of the most common allergens are placed on 8 rectangular pieces of tape as seen below.  No needles are involved.   On day 3 (Wednesday), you will return to the office to have the patches removed. The skin will be marked and examined for any preliminary reactions.  On day 5 (Friday), the skin is examined again for a delayed reaction, and tests results are reviewed with you.

+ What is the benefit of the ACDS Core Allergen series that we use in our office vs. the T.R.U.E. test?

At Monarch Dermatology, we use the American Contact Dermatitis Society Core Allergen Series for patch testing.  It is a comprehensive series that tests for 80 of the most common allergens in North America.  While the T.R.U.E. test is convenient and easy to apply, it only tests for 36 allergens and can miss a significant percentage of contact allergens.

+ What does a positive reaction look like?

Your doctor will review your results when the patches are removed.  Positive reactions range from mild redness with a little swelling to bright red, blistered skin, as seen below.

+ What happens if I am not allergic to any of the tested substances?

Negative results are common (~25%).  Patch testing helps to narrow the potential allergens that are causing your reaction.  If the test is negative, this is also important information as it tells us that you need not avoid the tested substances.  Please note that patch testing does not always explain the cause of a rash and does not include environmental or food allergy testing.

+ Will insurance cover my test?

We will contact your insurance and confirm approval prior to scheduling your appointment.  Most insurance plans cover patch testing to a great extent, but you may incur some personal charges.  Co-pays are collected on the 2nd and 3rd visits and may be collected on the 1st visit depending on your insurance.  Any deductibles that have not been met may also require additional payment.

+ What are the disadvantages of patch testing?

There are visits in one week.  2) You cannot let water touch your back from Monday to Friday.  3)  The test area can become very itchy, although this is a good sign as it usually indicates a positive finding.  4) Depending on your insurance, you may be responsible for a copay on 2-3 of the three visits.

+ Where can I learn more about contact dermatitis?

The Contact Dermatitis Institute is an excellent resource for patients and has information sheets on the most common allergens –

During Patch Testing:

+ What do I need to know before my patch test?

Keep your back dry for the entire test period – no showering, heavy exercising, or excessive sweating.   Moisture on the back will cause the allergens to run together and/or the patch tests to come off, negating the validity of the test.  Sponge bathing and washing your hair in the sink is okay.
Do not use oral or topical steroids on the back for at least two weeks. Antihistamines (eg-Benadryl/Claritin) ARE okay.
Wear loose clothing during the test period.
Do not apply any fragrances or creams on your skin on the day of the test.
If you have excessive hair, shave your back prior to the test.
Avoid excessive sun exposure to the back for 1-2 weeks prior to test and during the test period.
Itching and burning are common – but DO NOT SCRATCH.
A flare up of your skin rash may occur during the test period.

+ What should I do if my skin itches or burns during the patch test?

Itching and burning are common side effects.  Try not to scratch at the test sites, because itching is usually a sign of a positive reaction and scratching the affected site can alter the results.  If you get a very strong reaction with intense itching, burning, redness or pain, contact the office immediately.

+ The patches are getting loose. What should I do?

Have someone press on the test patches.  You can also reinforce them with additional hypoallergenic tape on the edges of the panels. Panels that are removed or damaged will require a complete retest so avoid any unnecessary manipulation of the patches as well as any movements that could cause the patches to detach.

After Patch Testing:

+ I tested positive for an allergen. Now what?

You must try your best to avoid all products containing the allergen.  Check the ingredients of products that you are currently using and ensure that they do not contain the positive allergen.  Refer to your CAMP results for products that are considered “safe” to use.

+ How do I access my CAMP results?

There are several ways to view your unique list of products that are safe to use: 1) as a PDF which we will send to you via email, 2) on the CAMP app which you can download to your phone (iPhone/Samsung compatible), and 3) using your unique allergen identification code that you can enter into . To simplify the process of shopping for “safe” products, we recommend downloading the app. The CAMP app will allow you to easily search for specific types of products and brands that do not contain your list of positive allergens. For more information on how to use app, go to

+ What is an allergen identification code?

It is a unique code that you can enter into the CAMP website and/or app that automatically loads the allergens that are specific to you.  It is important to save this code because the list of “safe” products can change periodically.  In other words, manufacturers may change the ingredients of personal care products and the ACDS CAMP site updates the list accordingly.  So a product that you are using now may not contain formaldehyde, but in 5 years the manufacturers may add formaldehyde to it.

+ I am avoiding all the allergens that I tested positive to, but my rash has not cleared? Am I doing something wrong?

It can take up to two months of allergen avoidance for your rash to visibly improve.  Be patient and hang in there!  If your rash persists past this time, be sure that you are familiar with all of the alternative names for your list of allergens.  Sometimes the ingredients on the bottle may have a synonym for the allergen and you may not realize.

If you are interested in patch testing, Contact us today or call 732-739-3223 to schedule a consultation with Dr. Divya Bhatnagar . Together, you can discuss your concerns and determine whether patch testing is right for you.