Allergy test (Patch test)

Created: 03.08.2023

Created: 20.12.2023

Approved by: General Practitioner, Dr Binita Parmar

An allergy test can help confirm or rule out an allergy. The tests could include an allergy skin test, a blood test or a special diet. The allergy can result in, for example, Contact dermatitis, Hives or Atopic eczema.

How does the test take place?

In the allergy test, the test material is placed directly on the skin in small chambers usually on the back. The test material must remain on the skin for 48 hours, and the area must not be washed before this is done. The test is read after 72 hours and remains untouched for 48 hours. After 72 hours, the test will be read by the dermatologist, and you will receive information on whether or not an allergy has been detected, and possibly which products you should avoid coming into contact with.

Preparations at home before the test

In the last 2-3 weeks before the patch test, you should avoid applying topical steroids on your back (Hydrocortisone ointments and creams against Eczema). If you use Prednisolone tablets, the dermatologist will assess whether the test can still be carried out. You should avoid the sun on your back in the last 4 weeks before the test. If you suspect that you are reacting to particular products (cosmetics, creams etc.), you can bring these to the consultation.

During the procedure

During the procedure, the test material will be taped to the back using a plaster. The procedure lasts approx. 20 minutes. A new consultation with a Dermatologist is arranged to read the test after 3 days. Here you will receive information about whether an allergy has been detected, possibly which products you should avoid coming into contact with and what kind of treatment is recommended.

After the consultation

When the patch with the test material is on, you cannot wash the area where the tape is attached, avoid activity that induces sweat and do not expose the test area to the sun. Sunburn can reduce the test's reactivity and, in the worst case, give false negative results. Avoid scratching the patch, and preferably wear a top at night to prevent it from coming off while you sleep.

Possible side effects

Patch tests rarely cause complications. In some cases, the reaction to the test material itself can cause a severe rash, but this can be treated with topical steroids to reduce itching.

General Practitioner

At Dr.Dropin our experienced GPs provide a wide range of primary care services, similar to those provided by the NHS, either in the clinic or through video consultations.


At Dr.Dropin, you will receive specialist care from our expert Consultant Dermatologists provided by skindoc. With extensive experience from both public and private hospitals, we can assess and treat most chronic and acute skin disorders – either in the clinic, through video, or via a photo upload service.