Patch test for allergies

patch test · contact allergy test · skin patch testing · allergy test on the back

Patches with small amounts of substances that can cause allergy are stuck on your back. After 2 to 3 days, the doctor checks where the skin turned red.

When a rash or eczema appears after contact with something: metals, cosmetics, hair dye, gloves, or substances at work.

⏱ Duration: putting on the patches usually takes 15 to 30 minutes; you wear them for about 2 days; checks are on day 2 and day 3 or 4

Be sure to tell your doctor

What medicines you take, especially steroid tablets and drugs that suppress the immune system
If you used a steroid cream on your back in the last few days
If you recently had a tan or sunburn on your back
What you work with and what you suspect yourself
If you are pregnant

How to prepare

Skin on your back. Your back must be clean, with no rash or tan. Do not put cream on it on the day of the test.
Medicines. Do not stop anything on your own. Some medicines interfere with the test. Your doctor will tell you what to do and when.
Schedule. Plan for 2 to 3 visits within a week, and days without sports or the sauna.
Your own products. If you suspect your own cosmetics or a product from work, ask your doctor if you can bring it.

What to bring

Your referral
A list of your medicines
Your own products, if the doctor allowed it
An old T-shirt. Marker lines can stain clothes

How it goes

You undress to the waist and sit with your back to the nurse
Patches with small cells of substances are stuck on your back
The edges of the patches are marked with a marker
After 2 days, the patches are removed and the skin is checked
1 to 2 days later, there is a second check

What you'll feel

The patches themselves do not hurt
It may itch under them. Do not touch or peel them off
Redness where you react may last a few days

Afterwards

While the patches are on, keep your back dry: no shower on your back, no sauna, no sweaty exercise
Do not sunbathe until the test is over
If a patch comes loose, tape it back down and tell your doctor
You usually get the results at the last visit: what you react to and what to avoid

Contact a doctor straight away if

Severe itching, burning, or blisters under a patch: call your doctor. They will tell you whether to remove it
A rash all over your body, swelling, or trouble breathing: call emergency services

Common questions

Can I wash during the test?

You can carefully wash your legs and hair over the bathtub, but your back must stay dry until the test is over.

How is this different from prick tests on the arm?

A patch test looks for allergy from skin contact. Prick tests on the arm look for fast allergies, like to pollen, dust, or pet hair.