Excessive generalised hair loss from the scalp and sometimes other hairy areas of the body (e.g. eyebrows, pubic area, chest) may be a symptom of disease such as:
- sex hormone disturbances (e.g. pregnancy, menopause),
- an over or underactive thyroid gland,
- pituitary gland diseases,
- drugs used to treat cancer,
- radiation therapy,
- too much vitamin A,
- sudden and excessive loss of weight (e.g. anorexia nervosa).
Extreme mental or physical stress may also be responsible. Blood and other tests may be done to exclude specific causes but are often normal.
If a cause can be found this should be treated. When the cause is medication, the hair usually grows back when it is ceased.