Alopecia Hair loss is a common side effect of several chemotherapeutic drugs and cranial irradiation, although not all children lose their hair during drug therapy. It is better to warn children and parents of this side effect than to allow them to think that it is only a remote possibility. A soft cotton cap is the most comfortable head wear for children. Polyester increases perspiration and causes itching. Other options include scarves, hats, or a wig.