Patch testing is carried out before we apply hair colour to ensure the chemicals in the hair dye do not cause an allergic reaction with your skin. The main ingredient we are testing is paraphenylenediamine, which is often used in hair dyes as it produces a very natural look.
Patch tests will usually be done 48 hours prior to your appointment. The stylist will ask you a few questions to ensure it is safe to carry out the patch test and apply a small amount of the colour sample to your skin, usually just behind the ear. This should not be washed off for 48 hours unless it causes a reaction. Mild reactions to paraphenylenediamine usually presents as an itchy dry rash on the upper eyelids and/or the rims of the ears. More severe reactions cause marked reddening, blistering, and swelling of the eyelids, scalp, face, and neck.
If you have an allergic reaction to the patch test you should alert your GP to let them know that you have had an allergic reaction to Paraphenylenediamine. Your stylist will discuss alternative options for you.