It is normal for anyone to shed a few strands of hair every day from brushing, combing or washing. However, there is cause for concern when the scalp sheds more hair each day than can be replaced, resulting in thinning hair and balding. There are a number of causes of thinning hair which affect both men and women.
Also called androgenetic alopecia, pattern baldness is a condition that causes progressive thinning of hair in both men and women. Male pattern baldness, in particular, also causes receding hairlines as well as thinning of the hair at the top of the head (see Resources below).
When there is a history of thinning hair and baldness in the family, chances are higher that you will suffer thinning hair as well.
Hormonal changes that occur naturally as we age may also cause shrinkage of the hair follicles among some people.
Illness may cause thinning hair. Often, when illness is the cause, the hair growth rate and thickness typically returns to normal following recovery. Health conditions such as anorexia nervosa may, in themselves, be a cause for thinning hair.
Some prescriptions may have thinning hair as one of their side effects. These include amphetamines, lithium, anti-depressants, some diet pills and chemotherapy drugs.
Hair naturally gets stronger during pregnancy, but tends to weaken and shed in the 3 months following pregnancy. This thinning typically stops after this period.