Skin patch test: procedures, etc. • hello healthy

Function

What is the patch test for (skin patch test) done?

Patch test or skin patch test is a type of allergy test that is done to determine what triggers your allergies.

This skin test can only be done in a hospital or in a professional dermatology clinic.

Procedure

How to do a patch test (skin patch test)?

As the name implies, the doctor or immunology technician will glue pieces of cloth similar to patches (patch) on your skin, usually on your back. The sheet of cloth has previously been dripped with a little of the allergen extract that is suspected to be the trigger for your allergy.

However, before you put the patch on, your back will be cleaned first using soap and water by a nurse.

Here is a step by step skin patch test procedure:

• After the back is cleaned, the doctor will mark several points on the back with numbers.
• Each number on the back indicates an area for a different allergen.
• Each of these areas will then be attached to a patch with a different allergen content.
• You can go home and you may feel itching and redness on the skin. This is a normal reaction.
• Even if it itches, don't remove the patch without your doctor's permission. The patch should be left on the skin for 48 hours or two days. You will be asked to return to the doctor to remove it.
• On the second visit, the doctor will shine ultraviolet light on your back. This is done if you are suspected of having a contact allergy caused by light induction (known as Photopatch testing).

In general, it will take you about a week to complete this series of patch tests.

The following is an example of a test schedule that will be conducted per day of arrival:

1. First doctor visit (Monday): Clean your back and stick patch to be left on for 48 hours.

2. Second doctor visit (Wednesday): Patch or the patch will be removed. The doctor will diagnose your condition according to the reactions that appear on the skin on your back.

3. Third doctor visit (Friday): A second reading is taken and the results and reaction reports will be discussed with the dermatologist.

Preparation

What should be prepared before doing the patch test (skin patch test)?

Generally, the following things you should prepare before doing the alias patch test skin patch test:

• Avoid sun exposure for 1-2 weeks before the patch test, especially on the back.
• Do not use topical drugs (creams or ointments) on the back and any other areas patch will be affixed, at least 1 week prior to testing. However, you can continue to use the ointment in other areas where patch will not be placed.
• You can apply a moisturizer on the skin the day before skin patch test.

After-Test Care

What treatments can be done after doing the patch test?

During pasting or patch it's still on the skin, you shouldn't open it. You are also generally advised not to shower or wet your back until it is time to go to the doctor.

After all the readings the patch test or skin the patch is complete, the doctor will prescribe a topical steroid cream to treat the itching or rash.

Dos and don'ts

What to avoid before and after doing a patch test (skin patch test)?

• Avoid activities that make you feel hot and sweaty.
• Avoid baths or saunas.
• Avoid excessive twisting movements. It can take off patch from the skin of the back.
• Do not put any oil or cream on the back in the morning before doing the patch test.
• Keep the skin area dry until the day the doctor diagnoses your allergic condition.
• Avoid exposure to direct sunlight to the back in the previous days and during testing. This is because ultraviolet radiation can reduce the immune response in the skin.
• Cortisone, prednisolone or immunosuppressive drugs should not be taken, as they can affect the results skin patch test.

Test results

How to read patch test results (skin patch test)?

After 48-96 hours, the doctor will generally remove the patch that is stuck on your back. The doctor will then observe the reactions that appear in each area.

Here's how to read the results skin patch test:

• Negative (-): no reaction (meaning you are not allergic to the allergen).
• Irritant reaction (IR): sweat rash, follicular pustules and burning reactions.
• Faint / uncertain (+/-): skin gives rise to pink plaques.
• Weak positive (+): pink or red plaques appear on the skin.
• Strong positive (++): on the skin appear 'papulovesicles' which are small, raised, fluid-filled lesions.
• Extreme reaction (+++): blisters or ulcers appear on the skin.