Hair cosmetics.

Alterations in the cuticle, cortex, and medulla are necessary to modify the hair cosmetically. The hair can be modified externally by the use of shampoos to remove excess sebum, conditioners to restore shine, and styling aids to increase manageability. Several different formulations of all these products exist, depending on the needs of the patient. Furthermore, the hair can be modified both externally and internally through the use of hair dyes, permanent waving lotions, and hair straighteners. Use of these products causes external damage to the hair shaft by disrupting the overlapping cuticular scales, rendering the hair susceptible to static electricity and the effects of humidity while decreasing manageability and shine. Internal damage created by these products decreases the hair shaft's elastic properties, allowing increased hair breakage. The dermatologist can better aid the patient with hair difficulties if he or she has an understanding of the formulation and effects of products designed to cleanse, beautify, and modify the hair.