What is patch testing?
Patch testing is a test used to establish whether you suffer from contact allergy.
You will be tested with various substances that your treating physician has found relevant based on your medical history.
The various substances that most often cause contact allergy are commonly found in the environment both at home and at work.
These include metals, fragrances, rubber chemicals and preservatives.
How is patch testing performed?
The patches containing the different substances are placed on your upper back, attached with tape, and are to be left in place for 2-3 days.
Subsequently, the patches will be removed and a first test reading of any possible skin reactions will be recorded.
After an additional 1-2 days, the back will be reexamined for the second test reading followed by the third and final reading 1 week after the test was initiated.
Allergy to any of the tested substances will present as a characteristic red itchy spot on the back where the substance has been in contact with the skin.
You will need to attend the clinic a total of 4 times within 8 days to complete the patch test:
The tape strips containing the test material are applied to your back. If the tape loosens at home, you can use normal tape or band aid to re-secure it.
After 2-3 days, the nurse will remove the tape and outline the position of the test substances on your back using a yellow highlighting marker. The nurse will examine your back for any skin reactions.
After an additional 1-2 days, the nurse will reexamine your back for any skin reactions and re-draw the yellow markings.
Fourth and final visit
One week after the tape and test material was applied to your back, the nurse will examine your back for any skin reactions. Subsequently, you will see your treating physician to receive information on the results of the patch test.
Precautions during patch testing
- Avoid sun exposure and tanning of your back, from 14 days prior to the test and until the final examination of your back is done.
- Avoid using steroid cream on your back from 3 days prior to the test and until the final examination of your back is done.
- If you receive ongoing treatment with topical steroids, you can apply this to the remaining relevant areas of your body during patch testing.
- Do not use lotion or moisturizer on your back from 1 day prior to the test and until the last examination of your back has been made. You can apply lotion/moisturizer to the rest of your body.
- It is advised to wear an old t-shirt or similar while the test is carried out. The test substances are mixed with petrolatum containing coloring additives which can discolor your clothes. The yellow marker used to mark the test sites can discolor your clothes and bed linens.
- Avoid exercising during the 8 day test period.
- Avoid applying water to your back during the 8 day test period.
- Avoid scratching your back during the test period, as it can interfere with the examination of the test results.
- It can be necessary to postpone the patch test if you have severe eczema on your back
- Please, inform us if you are known to be pregnant or are breast feeding.
After the patch test
Occasionally, skin reactions at the test sites can occur up to 2 weeks after your last visit.
If you experience a red itchy spot at the test site on your back, which was not present at your last visit, please contact the clinic.
Rarely following patch testing, changes in skin pigmentation can occur. These can be seen as small areas with darker skin color. These skin changes most often disappear by themselves.
Upon your arrival, please check in at the reception at ”Hudsygdomme, klinik 1”, Gentofte Hospitalsvej 15, ground floor.
The patch testing will be performed at ”Kontaktallergi, klinik 1”, Gentofte Hospitalsvej 15, 2nd floor.
If you are to be tested with some of your own products, remember these for the first visit!