Caused by the hair dye hair dye allergy allergic contact dermatitis, light performance of the scalp swelling, itching, burning, severe scalp, neck and facial swelling occurs, blisters, streams of yellow water, or even purulent infection. Hair dye composition has called 'p-phenylenediamine' chemicals, easy to skin damage. The more frequent hair dye, the more closely chemicals attach hair and scalp, the greater the harm to the body, the greater occurrence of the chance of hair dye allergy.