What is skin patch testing?
Skin patch testing is a method of detecting an allergy to a substance that has come into contact with your skin. These substances may be found at work, at home or in your leisure activities. Examples include perfume, jewellery, clothing, cosmetics, medicines, chemicals or metals.
Skin patch testing only identifies the substance that affects you when it is in contact with your skin. Any dietary or inhaled allergens are not detected by a skin patch test.
Before your consultation
Please bring the following (if applicable) to your consultation:
- Any substance you suspect may cause your skin rash
- A list of prescribed medication or anything bought at your pharmacy
- Toiletries and skin care products you regularly use, including hair treatments and nail polish
If you think that a substance at your place or work is the cause, please try to bring a sample. If this is not possible, try to find out its chemical composition and concentration. If you are in contact with industrial chemicals, your company regulatory affairs or quality control department will hold chemical details.
What do the tests involve?
You are usually required to make three visits. On your first visit for consultation, the consultant dermatologist will review your skin history and ask you about your workplace and social activities before choosing appropriate substances to test.
You will then be given an appointment to see a nurse who will then apply a number of small aluminium discs containing a small quantity of the substance to be tested, and attach the ‘patch’ to your back using hypoallergenic tape. You will be asked to keep these on your skin, usually 48hrs, until your second visit to the nurse, when they are removed and any reactions are noted.
48 hours later, at your third visit, your back is examined by your consultant dermatologist who will discuss any reactions with you.
The skin patch is applied to your back for practical reasons, as it is the biggest surface area of skin and the patches are more likely to stay in contact there.
Core test substances:
- Cutting oils
- Epoxy resin systems
- Antibiotics; antiseptics; anaesthetics; corticosteroids and ophthalmics
- Perfumes, flavours
- Rubber chemicals
- Textile and leather dyes
- Bakery allergens
- Dental materials
- Hairdressing substances
- Metal compounds
- Plastic materials
- Shoe allergens
- Vehicles, emulsifiers
- Industrial biocides
- Photographic chemicals
- Sunscreen agents
Source: Albyn Hospital Skin Patch Test Patient and GP Leaflets