Patch testing

Where does patch testing take place?

Your patch testing will take place in Clinic 7 (seven), which is on level three in Addenbrooke’s outpatients’ department. You will be given a set time, but there can be a short wait in clinic before you are called in.

What is a patch test?

The aim of the patch test is to try to discover whether you are allergic to anything that is coming into contact with your skin.

Are the patch tests painful?

No. There are no injections involved in patch testing. The patches may feel strange stuck to your back, and may cause you to feel itchy. This is normal, and nothing to be concerned about. If the itching is severe, the patches may have to be removed. It is important to note the chamber number, and to contact the department.

Which substances do we test?

The clinic uses standard patch tests for substances which are most commonly known to cause allergies. You will be tested with these. You may have to complete a questionnaire, which can help to identify any further substances that should be tested.

Do I need to bring anything in with me to clinic?

If you suspect you may be allergic to certain creams, soaps, etc. (for example if they make your rash worse), it may be helpful to bring in with you the normal labelled containers of these things. This will allow us to identify ingredients that you may be allergic to. It may not be possible to patch test you with the substances you bring in.

Can I have patch testing if I am pregnant? Please let us know

Patch tests are not advisable if you are pregnant or breastfeeding. They can be performed after you have had your baby and no longer breastfeeding.

Taking medicines? Please let us know

• You should stop using strong topical corticosteroids (such as Betnovate/ Dermovate creams) three to four days before your patch test.
• Oral steroids, azathioprine or ciclosporin should be continued unless you are advised otherwise by the doctor.
• Creams and ointments should not be applied to the back for 48 hours prior to patching, as the chambers may not stick to your skin very well.
• If your back is hairy, it will help to shave the area the day before your first appointment. You can continue to use mild steroid creams such as hydrocortisone on other areas of the body.

Holidays in a warm climate? Please let us know

Please avoid sunbathing for four weeks prior to your patch tests as sun exposure or tanning may make the results of the patch tests unreliable.

How many appointments will I have?

You will have to come to hospital for three appointments. It is very important that you attend all these appointments. If you are unable to attend any of these appointments, we will not be able to carry out your patch tests. Please ring the clinic 01223 216234 to cancel your patch tests, so that we can offer your appointment to someone else.

Your first visit

The patch tests consist of hypoallergenic strips of tape. On each strip are 10 small chambers, each of which contains a different substance.

The patches are applied to your back and the position of each chamber is marked with a special skin marker pen. The patches will stay on for 48 hours. You need to keep your back dry during this time. We can give you a tight vest to wear to help keep the patches in place.

What should I wear?

For your first two appointments, we suggest that you wear an old, dark-coloured shirt or tshirt that will wash out easily, as the pen we use can mark clothing. We can give you a tight vest, which will help keep in place. You will need to keep your back dry.

Can I go to work?

Generally yes, but you should avoid excessive bending and twisting, as the patches may come off. It is also a good idea to avoid strenuous exercise. Be extra careful for the first two to three hours after your patches are applied. This is when the patches are more likely to come off.

Your second visit?

The patches are re-marked and removed, and the nurse takes the first reading. You will not have any more patches applied. No conclusions can be drawn from the patch test at this stage and we will therefore not be able to give you any results. You need to keep your back dry for the next 48 hours.

Your third visit

The final reading takes place. The doctor or nurse will discuss the results with you and give you information about any of the substances to which you have reacted.