Baldness is not caused by a disease but is related to aging, heredity, and testosterone. Genetic predisposition to lose hair is the main cause of most of partial or complete baldness. Other possible causes of baldness include hormonal changes brought about by thyroid diseases, serious illnesses, and medications such as chemotherapy, as well as excessive shampooing and blow-drying, emotional or physical stress, bald patches that develop on the scalp, and ringworm disease of the scalp. The body's failure to produce new hair is the main cause of genetic baldness.

The causes of male and female baldness are different. The presence of excess amount of male hormone testosterone is the main causes of male pattern baldness. The cause of female pattern baldness is different from that of men. Female pattern baldness generally relates to genetics, age, and male hormones that tend to increase in women after menopause. Another common cause of women's hair loss is the impact of traumatic events causing stress that interferes with normal hair growth. Pregnancy is a typical example of an event that checks the growth cycle of hair. Deficiencies in the immune system can also cause baldness. The use of oral contraceptives can result hair loss in females.

Hair basically consists of dead cells produced by natural processes. Hair loss can be natural or unnatural. Unnatural reasons for hair loss include the effects of major surgery, hormonal changes due to thyroid dysfunction, diabetes, and ingestion of pharmacological agents. Hyperthyroidism, hypothyroidism, and thyroid cancer are the main thyroid diseases that cause baldness. The use of certain medicines and abrasive hair grooming or coloring agents can result in baldness. Baldness can also be caused by improper nutrition as well as vitamin deficiencies. Chemical damage is the common cause for both female and male pattern baldness.