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Patch testing

This page will give you the information you will need before, during and after your patch testing appointments. It is not a complete guide, so if you have any queries please do not hesitate to ask a member of staff.

What is patch testing?

Patch testing is an established test to help your doctor determine if your skin condition is caused by an allergy to a substance/substances that are coming into contact with your skin at home, work or during leisure activities.

What will I be tested to?

You will be tested to around 40 standard substances that commonly come into contact with the skin e.g. rubber, chemicals, metals, perfumes and plants.

What should I bring to the patch testing clinic?

At the first appointment (Monday) please bring a list of prescribed and over the counter medication you are currently taking and all ointments and creams you have been using.

What does patch testing involve?

You will need to attend for three appointments in the same week. If you need to cancel any of these appointments, all three will need to
be cancelled and rebooked for another week. The appointments will be on a Monday, Wednesday and Friday.

The first visit (Monday): You will be seen a dermatology nurse who will explain the patch testing process and answer any of your questions and ask you to sign a consent form to proceed with the patch tests. The substances to be applied are usually applied to the back and in four or five panels which each contain 10 individual areas with a different substance. Your back may need to be shaved if there is excessive hair.

A skin marker pen is then used to draw around the panels to mark where they were applied. Tape may be applied over the dressings to keep them in place. The panels should remain in place until your next appointment on the Wednesday. You may be asked to wait about 30 minutes after the patch tests are applied to ensure you do not have an anaphylactic reaction to any of the substances so you may need to allow 60 minutes for this appointment. In certain circumstances splash proof panels may be used and you will be able to get a shower Monday and Tuesday but not from Wednesday to Friday.

The second visit (Wednesday): You will be seen by a dermatology nurse who will remove the tape and panels and re mark your back using the skin marker pen. You may need to wait 20 minutes to allow any redness from the tape to settle before any reactions can be noted. The nurse will record any reactions in your notes.

The third visit (Friday): You will be seen by a dermatology consultant or nurse and your back will be examined and any new or existing reactions recorded in your notes. Any reactions will be discussed with you and you will be given information leaflets about these to assist you to avoid them in the future. You may need to allow 30 minutes for this visit. It is possible that all the substances tested show negative reactions and this is sometimes helpful since, as far as we can the tests have eliminated any contact allergy as a cause for your skin problem.

Positive reactions can become red and itchy and can blister at the test site and this is a normal positive reaction. These reactions are usually evident by the Friday visit but can occasionally take longer. If you develop a late reaction, please contact the call centre or dermatology service using the contact numbers available within this leaflet.

Please inform us if

  • You are pregnant or breastfeeding
  • Have extensive eczema/rash on your back
  • Have had sun exposure to your back or used a sun bed in the two weeks before your patch tests
  • Are on a moderately high dose of steroids or taking immunosuppressant’s

During the week of your patch tests

Do not:

  • Get your back wet unless splash proof panels have been applied as discussed on the previous page (or any area the tests have been applied)
  • Wear your best clothes as the marker pen and substances uses for testing for allergies can stain clothing and may come through onto furniture
  • Expose your skin to the sun
  • Do anything strenuous that may make you sweat as the panels may come off
  • Scratch the areas being tested


  • Avoid sport or heavy physical work during the week of the tests
  • Wear and old bra/T-shirt during the week of the tests and wear a Tshirt/ vest to sleep in to protect the panels
  • Reinforce the dressings with tape if a patch begins to peel off
  • Note the time and date if a whole patch come loose
  • Contact the call centre or dermatology service if you have any concerns

Side effects

Side effects are rare but include: skin reddening, itching, blistering from positive test results which usually disappears after a few days. Persistent reaction to some reactions such as gold can persist for up to a month. A positive reaction may be accompanied by a flare of existing or previous eczema/rash. There may be an increase or decrease in pigment at the site of the tests. Infection or scarring but this is rare. Very rarely you can become allergic to one of the substances applied but in practice this does not seem to cause a long term problem.

Storage of patch test results

Used for research and shared with other centres. More information on patch testing can be found at: or:

Should you require any further information or advice with regards to your treatment please contact Ironstone Centre Dermatology reception on 01724 292 106 who can direct your call to an appropriate member of the team. You may also contact the Customer Care team if you are concerned or worried about you treatment.