Defined as partial hair loss, or the complete absence of hair from places where it would normally grow, this condition commonly affects the scalp. In principle, new growth replaces 50-150 hairs that fall daily. Since a hair lives on average five years, the small sebaceous gland should provide twenty renewals a lifetime. Some factors, however, may interfere with the capillary programming. When hair starts to fall out in handfuls, there is every reason to ask questions and to consult a doctor or dermatologist to determine the exact nature of the problem.