Alopecia means diffuse hair loss, most notably of the scalp, caused by administration of various drugs. In some cases, alopecia is an indication of an underlying medical concern, such as iron deficiency. It grows vigorously for two to four years, then entered a transitional phase in the short and then a period of rest for two to four months. Then, it enters its third phase, detachment. The head contains approximately 100000 average hair. Of these, up to 100 (about one in 1000) hangar every day. After shedding, the strong growth stages are entered again. Pattern loss is the most common cause of hearing loss and affects 70% of men and 15% of women.

Classical men baldness affects the temporal regions of the forehead and is usually accompanied by a diffuse thinning in which, after moulting, a percentage of hair does regrow. One reason for the "alopecia," is the gradual increase of a hormone called dihydrotestosterone, or DHT. With the aging, especially men, the enzyme that converts testosterone to DHT increases in the activity and a greater concentration of DHT are produced. Today, there are blocking agents that can be prescribed only remove this cause of hair loss. When the hair loss is in a defined part of the body, is is known as alopecia areata.

Alopecia Areata is thought to be an autoimmune disease affecting people exposed genetically sensitive to the ambiguity of environmental triggers, such as infection or emotional stress. AA can occur at any age, from infancy in the late decades of life. Congenital cases have been reported. Peak incidence appears to have been the age of 15-29 years. Alopecia Areata tends to occur more often in children, adolescents and young adults. Alopecia Areata in not contagious. It should not be confused with the shedding of hair that may occur as a result of the discontinuation of hormone estrogen and progestin therapy for birth control.

Hair loss associated with the end of the pregnancy. Alopecia Areata may regress spontaneously become chronic, diffuse or spread. Risk factors for chronicity include extensive involvement occurred before adolescence, atopy, and the participation of the periphery of the scalp (ophiasis). Hair does regrow within a year without treatment. A variety of treatments can be tried. The steroid injections, creams and shampoos (clobetasol or fluocinonide) to the scalp have been used for many years. Other drugs include minoxidil, irritants (anthralin coal tar or topical), and topical immunotherapy which are sometimes used in different combinations.