General Hair Loss

Anyone can experience hair loss; hair loss is not bound by age, sex, or ethnicity. The average adult head has between 100,000 to 150,000 hairs and sheds between 50 to 100 hairs daily. Normal shedding doesn’t usually cause noticeable thinning of scalp hair, because new hair is growing in at the same time. Hair loss occurs when this cycle of hair shedding and growth is disrupted or when the hair follicle is destroyed and replaced with scar tissue.

Symptoms

Hair loss can appear in many different ways and parts of the body. Some types of hair loss are temporary, and others are permanent.

Signs and symptoms of hair loss may include:

Gradual thinning on top of head is the most common type of hair loss, affecting both men and women as they age.
Circular or patchy bald spots usually affects just the scalp, but it sometimes also occurs in beards or eyebrows.
Sudden loosening of hair can be caused by a physical or emotional shock. Handfuls of hair may come out when combing or washing your hair or even after gentle tugging.
Full-body hair loss can be caused by some conditions and medical treatments, such as chemotherapy for cancer.
Patches of scaling that spread over the scalp is a sign of rignworm.

Causes

The exact cause of hair loss may not be fully understood, but it's usually related to one or more of the following factors:

Family history (heredity)
Hormonal changes can cause temporary or permanent hair loss. This could be due to pregnancy, childbirth or the onset of menopause. Hormone changes caused by thyroid problems might also affect hair loss.
Medical conditions (e.g. alopecia, scalp infections, lupus, sarcoidosis, lichen planus, trichotillomania)
Medications used for cancer, arthritis, depression, heart problems, high blood pressure, and birth control can cause hair loss.
Radiation therapy to the head
Physical or emotional shock (e.g. sudden or excessive weight loss, high fever, surgery, death in the family)
Certain hairstyles and treatments. Excessive hairstyling or hairstyles that pull your hair tight, such as pigtails or cornrows, can cause traction alopecia. Some hair treatments or hot tools can cause inflammation of hair follicles that leads to hair loss.

Risk Factors

There are a number of factors that can increase your risk of hair loss, including:

Family history
Age
Poor nutrition
Certain medical conditions, such as diabetes
Stress

Prevention

Here are some tips to avoid preventable hair loss:

Maintain a healthy lifestyle - eat a nutritionally-balanced diet and remain active.
Avoid tight hairstyles (e.g. braids, buns, or ponytails).
Avoid twisting, rubbing or pulling on your hair.
When washing and brushing your hair, begin combing at the ends and work your way up the hair shaft to prevent pulling out hair. Use wide-tooth combs or detangling brushes for minimal pulling.
Avoid harsh treatments such as hot rollers, curling irons, flat irons, and hot oil treatments. If used, modify temperature on tools to match hair texture (e.g. low temperature for fine hair).