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What are the Reasons for Hair Loss?

Hair may not be vital for our physical well-being, but it is an important aspect of our physical appearance and often determines how other people perceive us. Although people tend to associate hair loss with the male gender, the truth is that both men and women can be affected. Reasons for hair loss include hormonal imbalance, diseases and stress, to name but a few. It is often temporary and hair grows back once the underlying cause has been eliminated. In other cases, hair loss is permanent. Some causes are gender-specific, while others affect both sexes.

A glimpse into hair anatomy and growth

Hair structure and growth may seem simple at first glance, but they are actually quite complex. This partly explains why the solution to the problem of hair loss has been eluding scientists for so long. Hair consists of a follicle which roots the hair into the scalp and hair shaft (the visible part of the hair), made of a sturdy protein called keratin. Hair grows from the base of the follicle and gradually emerges through the skin. It is lubricated by sebaceous glands located within the hair follicles. Hair growth follows a cycle consisting of three distinct phases: anagen (growth), catagen (cessation), and telogen (rest). All three phases occur simultaneously. Hair growth and structure vary throughout the stages of life, under the influence of hormones.

Normal vs excessive hair loss

People shed an average of 50-100 scalp hairs daily. This is part of the normal hair growth cycle, as new hairs will grow in their place. In some people, follicles stop growing hair as years pass - part of the normal aging process.

When more hair is lost than regrown, we are talking about excessive hair loss. The medical term for hair loss is Alopecia. In most cases, excessive hair loss is temporary. Shedding will subside and hair growth will return to normal once the underlying causes for hair loss are remedied. This usually takes 3 - 4 months.

Causes of temporary hair loss

A number of conditions can cause hair to fall out temporarily. Common reasons include:

Alopecia areata

This condition is autoimmune in origin. The body fails to recognize its own tissues and engages its immune response against the “invader”. Hair falls out in patches.


Physical trauma (ex. surgery, car crash, severe disease) can trigger a type of temporary hair loss known as telogen effluvium (outflow). In this type of hair loss, the stressful event forces more hairs than normal into the shedding stage. Emotional shock can also result in hair loss, but this is less likely to occur. More often than not, it aggravates a pre-existing hair-shedding issue.


Hair loss is a side effect of certain anticancer drugs. It can range from slight thinning to complete baldness. This type of hair loss is referred to as anagen effluvium. Whether hair loss will happen or not depends on the drug type and dosage. Chemotherapy-induced hair loss occurs from the mode of action of cancer chemotherapeutics. Namely, these drugs are designed to interfere with the cancer tissue growth, characterized by rapid cell division. However, this action is non-selective, meaning it also affects healthy and rapidly growing cells, including hair. In addition to scalp hair, the eyelashes, eyebrows, armpit, pubic and body hair may also fall out. In most cases, hair regrows 3 – 10 months after the treatment.

Harsh hair care and styling

Aggressive haircare products and hairstyles, such as cornrows and tight ponytails, can damage the roots and lead to hair loss. This is known as traction alopecia.


Prolonged nutritional deficiency states, including malnutrition and starvation, can affect hair growth. Insufficient protein intake forces the body to rationalize its resources and build blocks by shutting down hair growth. The lack of vitamin B complex (notably B6 and B12) and iron can also be reasons for hair loss. Keep your food nutritious and avoid crash diets.

Thyroid imbalance

Chronic and severe hypothyroidism and hyperthyroidism can cause temporary hair loss. A successful treatment of the condition resolves the problem, but it may take several months for the hair growth to return to normal.

Permanent hair loss

Permanent hair loss, or Androgenetic Alopecia, is also known as male pattern baldness in men i.e. female pattern baldness in women. Causes include a combination of hereditary and environmental factors.

Androgenetic Alopecia is linked to elevated levels of DHT (dihydrotestosterone), a derivative of the male hormone testosterone, which women also have in minute amounts. In a word, DHT causes hair follicles to shrivel up, thus preventing normal hair growth.

Male pattern baldness

Usually starts as a receding hairline, progressing to baldness predominantly in the crown area (top of the head). Follicles at the back of the head and the sides are less affected.

Female pattern baldness

Manifests as hair thinning at the top of the head and eventually the sides. It usually starts at menopause, since during the reproductive years, the actions of DHT are counteracted by the estrogen hormone. In women, hair thinning rarely progresses to actual baldness. Without treatment, this type of hair loss is permanent.

Female hair loss

Some types of hair loss are gender-specific and affect only women, mainly due to differences in physiology. Common reasons for female hair loss include:

  • Iron-deficiency anemia. Women regularly lose iron as result of menstruation. Lack of iron can lead to hair loss.
  • Hormones and stress. The stress of childbirth and hormonal fluctuations after pregnancy can push hair follicles into the shedding phase. The condition typically abates in about three months after childbirth.
  • Birth control pills and polycystic ovarian syndrome (PCOS) can cause excessive hair loss and thinning in genetically predisposed women.

Is hair loss preventable?

There are several effective solutions available to help stop or reduce the rate of further hair loss. Rogaine foam (minoxidil), recommended for both genders, and Propecia pills (finasteride) for men can stop the progression of hair loss and even promote hair growth. Laser therapy can stimulate hair growth by exposing hair follicles to a light that is set at a specific wavelength.

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Published on March 19, 2015

By Advanced Hair Restoration