Hair growth happens in a cycle. Each strand of hair grows for 2 to 6 years, rests, and then falls out. New hair then starts to grow in its place. It is normal to lose 50 to 100 strands of hair a day. These are replaced by new hairs which grow back in the same follicles (part of the skin where hair grows from). Hair loss becomes a problem when new hair does not grow back or too much hair is lost. It usually starts slowly and may be patchy or affect the whole scalp. Hair loss can affect anyone - men, women or children.