there are many types of hair loss also called alopecia: gradual thinning of hair with age is a natural condition known as involutional alopecia. more and more hair follicles go into a telogen or resting phase and the remaining hairs become shorter and fewer in number. androgenic alopecia is another form of hair loss. it's a genetically predisposed condition that can affect both men and women. men with this condition can begin suffering hair loss as early as their teens or early 20s while most women don't experience noticeable thinning until their 40s or later. in men the condition is also called male pattern baldness. it's characterized by a receding hairline and gradual disappearance of hair from the crown. in women androgenic alopecia is referred to as female pattern baldness. women with the condition experience a general thinning over the entire scalp with the most extensive hair loss at the crown. patchy hair loss in children and young adults often sudden in onset is known as alopecia areata. this condition may result in complete baldness but in about 90% of cases the hair returns usually within a few years. with alopecia universalis all body hair falls out. tearing out one's own hair a psychological disorder known as trichotillomania is seen most frequently in children. telogen effluvium is hair thinning over the scalp that occurs because of changes in the growth cycle of hair. a large number of hairs enter the resting phase at the same time causing shedding and subsequent thinning.
what is hair loss?