This is why some hair colors cause skin rashes
Para-Phenylenediamine or PPD
This chemical present in hair dye causes allergic reactions. PPD is found in more than two-thirds of permanent hair colors and dyes. It goes deep into the hair shaft and follicle and binds to proteins in the skin. This ability of PPD makes it an effective contact allergen.
There are certain hair dyes that contain Cobalt, which is responsible for the pigment in light and medium brown hair colors and dyes.
Another chemical commonly found in solutions used to straighten or curl the hair is Glyceryl Thioglycolate. This is commonly used (color protection serums) along with hair dyes and colors and could also be a major cause for facial rash. Since it is not found in standard panels for testing contact dermatitis, it can easily be missed by any dermatologist performing test for contact dermatitis. Therefore, when you get a facial allergy, you must consider all the chemicals that could be a factor for skin rash.
It is obtained from coconut, which is often used by cosmetic companies to make soaps, shampoos, and other bath products. It is the chemical component that creates foam or bubble. Since it isn’t found in dyes and hair colors, it is the most overlooked reason for contact dermatitis of the face. Most people consider shampooing their colored hair immediately after the chemical treatment, which can expose them to the chemical component and trigger facial rashes.