Hypertrichosis is an abnormal amount of hair brought on by disease or injury. It produces excessive and abnormal growth of hair in comparison to individuals of the same sex, age, and race. The excess hair growth may or may not involve pigmented hair fibre. Hypertrichosis can develop all over the body or, more likely, it just develops in a small patch. Any hair bearing area of skin can be affected by hypertrichosis.
Hirsutism is excess terminal hair growth in women with a male distribution pattern.
The excess hair growth is limited to one or more areas including the moustache, beard, chest, and genital region. Hirsutism is usually associated with increased or reduced exposure to hormones. Primary causes of hypertrichosis are listed and briefly explained below. Congenital hypertrichosis is a term for any excessive hair growth visible on a child at birth. The hair growth can be excessive for a wide variety of reasons and may involve the entire body with a mass of fine long hair, diffuse excess hair, or may be restricted to specific areas.