Painful scalp when dyeing hair may be caused by irritant dermatitis caused by some kind of chemical used in hair dyeing that irritates the skin on the head. Irritant dermatitis may only manifest as mild itching when it is not severe, but if the inflammatory response is significant, there may be painful symptoms accompanied by redness and even inflammatory infiltration. Once this happens, hair coloring must be stopped immediately and oral antihistamines and glucocorticoids must be taken if necessary to control the development of inflammation.