It is normal to lose 50-100 hairs a day, so it is not necessarily a worrying sign to see hairs fall out. There are various possible causes of hair loss, the major ones are; stress, drugs, skin disorders, testosterone, menopause, iron deficiency, genetics and aging. Hair loss is a widespread condition.
Physical or mental stress can cause temporary hair loss, it often occurs 2-3 month after the stressful event or period started. The reason for this is that the hair follicles enter the telogen phase prematurely, this causes them to stop growing new hairs and to shed hairs. Usually the hair loss will recover completely once the stress has been removed.
Many drugs can also cause hair loss, though there many be a delay between taking the medication and the actual hair loss, so any medication is being taken it is important to consult a doctor to identify if this could be a side effect of the drug being taken. Following are some drugs which may cause hair loss:
Some disorders of the skin, for example psoriasis, may cause hair loss. However once the skin problem is treated the hair should regrow.
The main male hormone testosterone is indirectly a major cause of hair loss in men, it is a direct result of the hair follicles responding to male hormones. However it due to the follicles being more responsive to the hormones that this occurs, rather than their being too much testosterone. The skin of the scalp changes testosterone to Dihydrotestostrone (DHT). Some hair follicles are especially sensitive to DHT and they shrink, this is more likely to happen to follicles on top and front of the head. It is interesting to note that DHT helps the growth of beard and chest hair, and it is not known for certain how DHT causes this opposite effect. Exercise also has an effect on DHT.
It is more than likely that if you have any relatives who are bald then this is likely to be a cause of hair loss in you. This can be inherited from either the father's side or the mother's side.
Hair loss increases likelihood increases with age. By 35, 40% of men have noticeable hair loss, while by 60 65% do. Also elderly hair tends to be more thin and fine giving more of an appearance of hair loss.
After the menopause thinning of the hair is more pronounced, by the age of 50 more than 50% of women have thinning hair.
If iron in the body is low then this may cause hair loss also, this is generally more a problem with women.
It is common for women to lose a great quantity of hair for some months after child birth, but the hair should come back naturally.
Read about hair loss treatments.