Last Updated on 5 years by Sophie

Contact allergy patch test procedure

Contact allergy is a sensitivity reaction of the skin which some people develop on contact with substances usually harmless to others.

These substances, or allergens as they are called, can enter the skin and cause the skin to react in a rash.

The most common allergens are nickel(available in most costume jewelry),, cosmetics, dyes, perfumes, metals, industrial chemicals, rubber products, medicaments. People can be allergic to anything even food.

In many cases, removing the cause of  allergy will solve the problem, understanding what causes your allergic reaction and knowledge is important in dealing with it, Contact allergy once developed is usually life-long problem.

Treating or dealing with allergic condition requires early proper diagnosis and accurate information from patient on how it started and when, is it the first time and so on.

When an allergen comes into contact with the skin, immune cell in the skin react by producing active chemical substances and these substances produce inflammation resulting in an itchy rash. The sensitivity may not appear fast or suddenly, but only after repeated exposure to the offending allergen.

How is contact allergy is confirmed?

When a patient or a dermatologist suspects an allergy, information on home and work condition is recorded, living habits and when the symptoms appear.

The dermatologist will decide from this what test will be necessary, and then carry out skin test which include patch testing or prick testing to different materials, and the results of these tests will help understanding your case and what treatment is the best.

Patch test procedure

You may be allergic to substance that you have come into contact with. A patch test procedure will help determine what is the substance that you are allergic to.

During the test pieces of tapes will be plastered onto your back or shoulders. To make testing procedure successful you need to follow these  rules:

1- Leave the patches in place until they are removed by the dermatologist.

2- To prevent false results, you should not wash your back or shoulders and avoid exposing affected areas of your skin to sunlight or ultraviolet light.

3- Avoid strenuous exercise that will cause excessive perspiration, as well as movements that may cause the patch test to fall.

4- Do not allow the patch to be loose and not attached to the skin as this will affect the accuracy of the test.

5- Do not scratch your skin during when the patch is attached.

6- Batch reading will be taken twice during the test after third day and seventh day.

7-  You should not wash or sunbathe the tested area after the patch is removed, your dermatologist will let you know when the test is over.

In some cases the reaction to the test patch is sever, and in such cases remove the patch and consult your doctor.

If you are using any medications or creams your doctor must know before the test. It’s normal the area where the patch applied will remain red for three weeks or less.