What Causes Hair Loss?

On average, people normally shed 50 to 100 hairs a day. This usually doesn’t cause noticeable thinning of scalp hair because new hair grows in at the same time. Hair loss occurs when this cycle of hair growth and shedding is disrupted or when the hair follicle is destroyed and replaced with scar tissue.

What Are the Risk Factors for Hair Loss?

So, what causes hair loss? There is more than one answer. While most hair loss is not associated with systemic or internal disease, hair may simply thin because of predetermined genetic factors and the overall aging process. Many men and women may notice mild physiologic thinning of hair starting in their 30s and 40s. Life changes, including illness, emotional trauma, protein deprivation, and hormonal changes like those in pregnancy, puberty and menopause also may cause hair loss.

To understand the risk factors and causes more in depth, we must look at family history, hormonal changes, medical conditions, and medications.

Family History

The most common cause of hair loss is a hereditary condition called male-pattern baldness or female-pattern baldness. It usually occurs over time and in predictable patterns (i.e. a receding hairline or bald spots in men and thinning hair in women).

Hereditary also affects the age at which you begin to lose hair, the rate of hair loss and the extent of baldness. Pattern baldness is most common in men and can begin as early as puberty, which may involve both hair thinning and miniaturization (hair becomes soft, fine and short).

Genetic hair loss is the most common cause of hair loss. The gene can be inherited from either your mother’s or father’s side of the family, though you’re more likely to have it if both of your parents had hair loss.

Hormonal Changes and Medical Conditions

A variety of conditions can cause hair loss, including:

• Hormonal Changes: Hormonal changes can cause temporary hair loss. This could be due to pregnancy, childbirth or the onset of menopause. Hormone levels are also affected by the thyroid gland, so thyroid problem may cause hair loss.
• Patchy Hair Loss: This type of hair loss occurs when the body’s immune system attacks hair follicles, causing sudden hair loss that leaves smooth, roundish bald patches on the skin.
• Scalp Infections: Infections, such as ringworm, can invade the hair and skin of your scalp, leading to patches of hair loss. Once infections are treated, hair generally grows back.
• Other Skin Disorders: Diseases that cause scarring may result in permanent loss at the scarred areas.
• Hair-Pulling Disorder: This condition, also known as trichotillomania, causes people to have an irresistible urge to pull out their hair, whether it’s from the scalp, the eyebrows or other areas of the body.


Hair loss can be cause by drugs used for cancer, arthritis, depression, heart problems, high blood pressure, and birth control. Intake of too much vitamin A is also what causes hair loss.

Other Causes of Hair Loss

Hair loss can also result from the following:

• Radiation Therapy to the Head: The hair may not grow back the same as it was before.
• A Trigger Event: Many people experience a general thinning of hair several months after a physical or emotional shock such as sudden or excessive weight loss, a high fever, surgery or a death in the family. This type of hair loss is temporary.
• Certain Hairstyles and Treatments: Excessive hairstyling or hairstyles that pull your hair tight, such as braids or cornrows, can cause this condition. Hot oil hair treatments and permanents can cause inflammation of hair follicles that leads to hair loss. If scarring occurs, hair loss is permanent.
• Telogen Effluvium: This condition occurs after pregnancy, major surgery, drastic weight loss or extreme stress, in which you shed large amounts of hair every day, usually when shampooing, styling or brushing. It can also be a side effect of certain medications such as antidepressants, beta-blockers and nonsteroidal anti-inflammatory drugs.

Schedule a Consultation

If you or someone you know experience hair loss, it may be time to discuss a prevention and treatment plan with your doctor. The form of treatment will depend on the cause of your condition.

Join our many satisfied patients, and schedule an appointment with Sleep MD NYC today, for treatment options.