The normal cycle of hair growth lasts for 2 to 3 years. Each hair grows approximately 1 centimeter per month during this phase. About 90 percent of the hair on your scalp is growing at any one time. About 10 percent of the hair on your scalp, at any one time, is in a resting phase. After 3 to 4 months, the resting hair falls out and new hair starts to grow in its place.
It is normal to shed some hair each day as part of this cycle. However, some people may experience excessive (more than normal) hair loss. Hair loss of this type can affect men, women and children.
Hair Loss and Its Causes
What is the normal cycle of hair growth and loss?
What causes excessive hair loss?
A number of things can cause excessive hair loss. For example, about 3 or 4 months after an illness or a major surgery, you may suddenly lose a large amount of hair. This hair loss is related to the stress of the illness and is temporary.
Hormonal problems may cause hair loss. If your thyroid gland is overactive or underactive, your hair may fall out. This hair loss usually can be helped by treatment thyroid disease. Hair loss may occur if male or female hormones, known as androgens and estrogens, are out of balance. Correcting the hormone imbalance may stop your hair loss.
Hormonal problems may cause hair loss. If your thyroid gland is overactive or underactive, your hair may fall out. This hair loss usually can be helped by treatment thyroid disease. Hair loss may occur if male or female hormones, known as androgens and estrogens, are out of balance. Correcting the hormone imbalance may stop your hair loss.