Alopecia is the general medical term for hair loss. There are many types of hair loss with different symptoms and causes. Male-pattern baldness is the most common type of hair loss, affecting around half of all men by the age of 50. It usually starts around the late twenties or early thirties and most men have some degree of hair loss by their late thirties. It is not clear if female-pattern baldness is hereditary and the cases are less well understood. It tends to be more noticeable in women who have been through the menopause. Are you experiencing hair loss? Are you worried about thinning hair or baldness? What can you do to prevent it?