Prof. Amir Horev

Dermatology and Venereology Specialist and Pediatric Dermatologist

The most comprehensive test for contact skin allergy

A patch test is designed to check whether the patient suffers from a skin allergy to topical preparations that come into contact with the skin. Patients who have a skin rash that is suspected of being contact dermatitis undergo the test to detect the "allergen" - the chemical component that causes the skin allergy.

During the test, various patches containing various allergens, known as common allergy triggers, are stuck to the subject's back for 48 hours. After 48 hours, the subject returns to the doctor, and the patches are removed from the skin. If the test is "positive" and a skin allergy is detected, the subject receives the necessary information about the specific allergy, and how to avoid exposure or contact with the allergenic substance.

It should be noted that the patch test tests for skin allergy by contact and is different from allergy tests performed by an allergist (which include blood tests (RAST) and skin prick tests).

Instructions for the test at the clinic:

If you have recently been exposed to the sun on a massive scale, such as repeated treatments at a tanning salon, baths or sun rays – you must inform the doctor or nurse. After exposure to the sun, you must wait, usually 3 weeks, to perform the tests.
The week before the test – you must use liquid soap for the body: Camille Blue Hypoallergenic Soap for Sensitive Skin by Dr. Fisher, you must stop applying cosmetic or medical creams (steroids).
3 days before the test – do not apply body lotion, deodorant, perfume, hair gel or mousse, nail polish, facial shaving cream or anything else. You must also remove jewelry such as: watches, necklaces, bracelets, rings, earrings, etc.
On the day of the test (on Mondays of the week), you must arrive after a thorough shower.
For the three days of the test, you must wear a T-shirt made of full cotton and not synthetic fabric.
For women – it is recommended to come without a bra for the three days of the test.

The test procedure

The patches for the swab tests will be placed on your back or sides of the body.

After the test

After the patches are placed, you will be discharged home for 48 hours. The following precautions should be taken:

Do not get the patches wet!! Therefore, it is recommended to wash only the lower half of the body. Under the armpits with a damp towel and lukewarm water.
Do not scratch or rub your back.
Do not apply cream or ointment to any area of the body.
It is recommended to avoid physical activity that causes excessive sweating, which may cause the patches to loosen and disrupt the materials in them.
It is recommended to avoid eating spicy foods and drinking very hot drinks that cause sweating.
Do not wear warm clothes or cover yourself with blankets that cause sweating.
If the patches are placed on your back – it is recommended to lie on your stomach and sides.

48 hours after applying the patch – Wednesday

The patches will be removed by the nurse and marked with a special marker that comes off when you shower
After the doctor's examination, you will most likely also be scheduled for a check-up after 72 hours – on Thursday

Side effects

Usually there are no side effects and the patches are well tolerated.
There may be a sensitivity to the patches or one of the substances, manifested by itching in the patch area. You can take an antihistamine pill to prevent itching (for example, Fenistil, Lorazepam, Telfast, Ereus, etc.).
In extremely rare cases, shortness of breath, rash or swelling of the lips, face and around the eyes may occur. In this case, contact your doctor or the emergency room.