Skin tests are carried out by hairdressers before a client has a hair colour applied. This is so important, as it indicates whether they are going to be allergic to the colour they are having put onto their hair. All salons should carry this out – if they don’t offer to before you hair colour, and you are a new client, you should ask them about it to make sure you are going to be safe. Equally, if you apply a colour at home, you need to perform a skin test with a sample of the colour first.
You can become allergic to a colour at any time. It doesn’t matter if you have had it applied 20 times before – you could suddenly have a reaction. If you have the colour on a regular basis, that is fine, as the colour will act as your skin test. However, if you wait a while in between, make sure you have you colour patch test before your next hair appointment.