Less common causes of male hair loss

Although male pattern baldness is the most common cause of hair loss, there can sometimes be other explanations:

• Telogen effluvium. With this condition, hair is shed very rapidly when the growth cycle is interrupted by a specific event such as illness (e.g. cancer, kidney failure, anaemia), surgery, taking certain prescribed drugs (e.g. Prozac for depression or Inderal for high blood pressure) or even extreme stress. You could notice lots of hairs coming out when you comb or shampoo your head. Often hair is found on the pillow after sleeping. However, it's unusual for more than 50% of the hair to be lost.
• Anagen effluvium. Here, the hair follicles are damaged – usually as a result of cancer chemotherapy – and there's a sudden reduction in the growth rate of the hair, accompanied by thinning and breakage of the hair shafts. Typically a patchy kind of hair loss sets in, sometimes leading to the loss of 90% of scalp hair.
• Thyroid deficiency. The thyroid gland, located in the neck, controls metabolism in the body and has a profound effect on hair growth. If the thyroid gland is underactive hair becomes brittle, dry and thin. This can be the first sign of thyroid problems.
• Iron deficiency. With a good normal diet, most men take in more than enough iron to cover their needs. In vegetarians, or those who avoid red meat and liver, the intake can be insufficient and this can lead to depletion of the body's stores. Iron has a major impact on hair growth, and if body stores are low, hair fall can increase and the hair can become thinner.
• Alopecia areata. This results in the sudden loss of hair in oval patches from the scalp. These patches are surrounded by characteristic broken, tapered hairs, known as "exclamation mark" hairs. The causes of this condition are unknown, although there is often a family history of the disease and it may occur alongside Down's syndrome, Addison's disease or vitiligo.
• Alopecia totalis. In this rare condition, which is related to alopecia areata, all the hair on the scalp is lost, along with eyebrows and eyelashes. In alopecia universalis, all the body hair is lost as well.
• Traumatic alopecia. This is patchy hair loss and twisted broken-off hair which may due to you (or your hairdresser) treating your hair or scalp badly. Even wearing a tight hat or baseball cap can damage the hair in this way.
• Fungal infection of the scalp. This can produce itchy bald patches. A bacterial infection may lead to a red, scaly scalp with patchy or diffuse hair loss. The skin disease psoriasis may also be linked to hair loss.
• Trichotillomania. This form of baldness is linked to a mental illness in which someone deliberately pulls out his or her hair. It's seen as a form of self-injury, where extracting hair brings temporary relief from mental pain.