Hair dye products contain a wide range of chemicals, any of which can trigger sensitivities and allergic reactions in susceptible individuals. One such chemical, paraphenylenediamine (PPD) is commonly found in permanent hair dyes and is known to cause sensitivity for some people. If you are at a hair salon and feel discomfort or concern after a dye has been applied, make sure you alert your hairdresser immediately. If you have had a reaction previously, ask your hairdresser to do a skin patch test first before applying to your scalp. Allergic reactions can be very serious. It is important that you try and reduce your exposure and build your immune system if you are known to suffer from sensitivities. If you have severe reactions consult your General Practitioner who may refer you to an allergy specialist.