Doubts concerning the action of hair cosmetics and the health of both body and hair are more frequent in the dermatological visits. Dermatologists need no only to enrich the knowledge of scalp diseases but also of molecular interactions of cosmetics used in hair fi ber, including the infl uence of such products when absorbed by the epithelium of the scalp. The amount of medical visits increases every day to fi nd out which techniques and chemical products are best indicated to enable the desired changes in hair from its natural appearance and, at the same time, to keep the hair healthy and beautiful. In this article, divided in two parts, we discuss the hair physiology, structure and chemical nature, as well as the agents used for its smoothing, coloring, hygiene and cosmetic treatment, and the consequences that such procedures can have on overall health, including their use safety during pregnancy and lactation.

Keywords: HAIR PREPARATIONS, HAIR, HAIR DYES

The authors complement the fi rst article on the approach of dermatological aesthetic hair treatments. This article addresses the ultimate hair straightening with major straightening legalized – sodium, lithium and guanidine hydroxides and ammonium thioglycolate –, their differences, mechanisms of action, indications and safety to human health. Besides these straighteners, we discuss the illegal and indiscriminate use of hairdressers salons in Brazil in the group of aldehydes (formaldehyde and glutaraldehyde) for smoothing hair. This study focuses its legal implications and public health, carcinogenic potencial and the identification of such filings with ANVISA. Also studied the shampoos and conditioning agents indicated for treatment of the hair shaft. Finally, we discuss the implications of hair care in general health of the hair shaft and the scalp.