Hair Loss - Cause
Losing a lot of
hair (more than 100 hairs a day) can be caused by
inherited factors, disease, stress, medicines, injury, aging, or hair care.
Inherited hair loss
The most common cause of hair
genetics—you inherit the tendency to lose hair from
either or both of your parents. This is called male-pattern hair loss or
female-pattern hair loss. The medical term for this type of hair loss is
In this type of
hair loss, your
genes affect how your hair grows. They trigger a
sensitivity to a class of hormones called
androgens, including testosterone, which causes
hair follicles to shrink. Hair follicles are the openings that hair grows from.
Shrinking follicles produce
thinner hair and eventually none at all. Men generally develop bald spots on
the forehead area or on the top of the head, while women often have thinning of the hair on the top of the head. About half of all people have
inherited hair loss by about 50 years of age.
Other causes of hair loss
Different types of hair loss may have different
causes. Common causes of hair
- Ringworm of the scalp, which is common in
- Mental stress or physical stress, such as recent surgery,
illness, or high fever. You may have a lot of hair loss 1 to 3 months
after severe physical or emotional stress. Your hair usually will grow back
within a few months.
- Hair styling and products. Pulling your hair back too
tightly or wearing tight braids or ponytails can cause hair loss. You may lose
hair around the edge of the hairline, especially around the face and forehead.
Using curling irons or dyes a lot can also result in hair loss. Hair
usually grows back when you stop doing these things.
- Age. As you age, your hair tends to break more easily, and hair
follicles do not grow as much hair.
- Poor nutrition, especially lack of
iron in the diet. Hair returns after you change your
diet to get enough of these nutrients.
- Thyroid diseases, including
Other causes of hair loss include:
- Alopecia areata, an
autoimmune disease in which your immune system attacks
hair follicles, resulting in round hairless patches on any area of the
scalp or body. Severe cases involve many bald patches of hair or complete loss
of hair on the scalp or body, although in some cases there is hair thinning
without distinct patches of baldness. The hair loss usually is not permanent. Hair grows back within 1 year for many people.
- Diseases, such as
syphilis, or cancer. Hair may grow back on its own,
although you may also need treatment.
- Side effects of
medicines or medical treatments, such as blood
thinners (anticoagulants) or
chemotherapy. Hair usually grows back after you stop
using the medicines or when the treatment is over.
- Trichotillomania, a compulsive behavior in which a
person pulls hair out of the scalp, eyelashes, or eyebrows. There is usually
mounting tension before pulling and a feeling of relief afterward.
Trichotillomania often results in noticeable hair loss.
- Injury to
the scalp, including scarring.
- Changes in hormone levels. Childbirth, taking birth control
pills, or changes in a woman's
menstrual cycle can affect the hair growth cycle and
cause hair loss. Hair usually will grow back.