What Causes Hair Loss?

In androgenetic alopecia, some hair follicles genetically produce a substance that reacts with male hormones. As you get older, this reaction eventually causes the follicle to shut down. Female diffuse baldness happens more slowly than male pattern baldness because women have a small amount of male hormones in their bodies. A hormone imbalance may make the problem worse.

Temporary hair loss may result from any shock to the body's systems. Reasons include starvation, systemic infection, childbirth, thyroid or immunologic disorders, drugs (especially chemotherapy for cancer), or stress. Hair follicles can be destroyed permanently by scarring from burns, severe scalp infections, x-ray therapy, or skin disorders. Damage may also result from tight hairstyles over a long period of time, chemical treatments such as hair coloring or permanents, or habitually pulling out hair. A fungal condition, called tinea capitis ("ringworm of the scalp"), also causes hair loss. With alopecia areata, or patchy hair loss, the body's immune system attacks the hair follicles, which grow smaller and don't produce as much hair. The condition may have a genetic factor, and often tends to occur in times of stress.