Alopecia is the medical term for hair loss. Hair loss is most commonly due to heredity. Other causes include age, immune system dysfunction, medications, and cancer treatments like chemotherapy and radiation; some systemic disorders such as psoriasis; nutrient deficiencies like iron deficiency, and thyroid disease. It can also be associated with hormone imbalances, childbirth, illnesses, infections, certain hair styles, and hair care.

Your hair grows from a root inside a hair follicle. Scalp blood vessels carry nutrients to the roots to support hair growth. Hair follicles continually interact with the rest of the body through biological signals that tell the follicles when to cycle. Growth and shedding are random. The average healthy person will shed 50-100 dead hairs per day. Follicle activity and hair production also depend in part on hormone control.

What are the different types of hair loss?

Androgenetic alopecia is hereditary hair loss. It is the most common cause of hair loss in men and women, affecting 70% of men and about 30% of women or about 80 million Americans.  Male pattern baldness assumes a common pattern and typically becomes noticeable in the third decade. Female pattern baldness is diffuse thinning of the hair on the scalp and widening of the part. It typically becomes noticeable around ages 40 to 50.

Pattern hair loss is controlled by the male hormone, testosterone. Scalp hair follicles metabolize testosterone which shortens the growth phase of the hair cycle and leads to a miniaturization of the hair follicles, causing hair growth to slow and finally stop. Treatments can slow hair loss and regrow hair.

Alopecia Areata is patchy hair loss caused by immune system dysfunction. For unknown reasons, the immune system attacks healthy hair follicles and the hair falls out and does not grow back. It may appear as patchy balding or total balding. Alopecia areata can happen suddenly and may affect body hair including the eyelashes and eyebrows, as well as scalp hair. Medical treatments can help regrow hair.

Telogen effluvium is another common form of hair loss but doesn’t usually lead to baldness. Instead the hair thins usually at the crown and temples. It results as a response to stress, fever, surgery, childbirth, gastric bypass surgery, iron deficiency, some medications, oral contraceptives, and chronic thyroid disease. It often becomes noticeable three months after the event that caused it and is usually short lived, once the trigger is removed. However, Telogen effluvium can become chronic if it lasts longer than six months, and in some cases can last for years.

Hair loss can also result from ringworm, a fungal infection; another autoimmune disease; inflammatory disorders; scalp skin disease; and hair products or styling.