Allergy Patch Testing for Eczema
This clinic is run by a team of Doctors and Nurses led by Dermatology Consultant Dr Chandhi Ondhia, Prof Nick Levell and Specialist Nurse Sarah Catten
This type of testing can be helpful in patients with eczema or dermatitis (two words for the same thing!) limited to a localised area, for example on the face.
It tests specific allergens which can be in products which are in contact with the skin, to see whether they are causing or making your skin dermatitis worse.
It is not a test used to determine food allergies and intolerances.
Patch testing does not involve needles, but instead, sticky patches, in which many small aluminium chambers are applied, each containing a small amount of an allergen to be tested.
The photograph shows a close up of the patches which are applied to the skin.
An information leaflet on patch testing can be found at Norfolk and Norwich University Hospitals NHS Foundation Trust » Patch Test Information v7 and Patch testing – BAD Patient Hub
What does patch testing involve?
Usually 40-100 chemicals are applied, using sticky tape, to the back on Monday. Patients then come back to the clinic to have readings twice, usually on Wednesday and Friday when further management of your skin condition will be discussed.
If it is suspected that the allergy may be triggered by sunlight, we may shine ultraviolet light onto the skin on Wednesday, 48 hours after applying the chemical.
Does it hurt?
It can feel rather unpleasant having sticky tape all over the back for a few days, however this is usually tolerated. If you develop a strong reaction, it can become very itchy, and if this happens, we will give you a treatment for this. Men with hairy backs usually find removal of the tape rather uncomfortable.
What should I do or not do?
Please do not wash the back, shower or bath, while being tested or the tapes will fall off. Avoid vigorous exercise, bending and stretching the back.
We are unable to test you if you have had sun on the back within 6 weeks as the reactions are usually supressed. We use a marker pen on the back, so wear an old shirt or vest and not your best silk top!
What sort of chemicals are used?
We test you to substances that people commonly come into contact with every day for example through touching coins, rubber gloves, clothes, shoes, newspaper, soaps, shampoos, make-up, household cleansers, plants, glues and items at work.
Can I bring things to test?
If there is something you are suspicious that makes your skin worse, then bring it along on the first appointment. Some things such as strong detergents and corrosive chemicals can’t safely be tested but we will advise you at this appointment.
Can anyone not be tested?
We review patch testing in young children on a case-by-case basis since sometimes they will not tolerate sticky tape all over their back for a few days.
High doses of steroid tablets prevent the patches reacting, as do medications that suppress your immune system, therefore please let our team know if you take these, before the appointment.
Excessive sun exposure on the back can also prevent the patches reacting for six weeks afterwards.
We do not test people who are pregnant or breast feeding.
Does patch testing identify allergies due to food, medicines, things in the air and bee stings?
No. Other mechanisms in the body can cause these allergies and these are tested for in other ways in an allergy clinic.
Once you have been referred by the Dermatologist for Patch Testing, you will be contacted and appointments arranged, once you are at the top of the waiting list.
Please note that The Norfolk and Norwich provides a childhood allergy service through the Paediatric team, but unfortunately there is not an adult service at this hospital, and patients requiring Allergy input are referred to Cambridge University Hospital.