Hair Loss Causes and Risk Factors

Hair loss is a common problem. It can affect only the scalp or whole body or any other part of the body where hairs are present. There are various causes for hair loss as well as various risk factors for it. An individual, on an average normally shed 50 to 100 hairs a day. However, this rate of hair fall do not cause any problem, because new hairs also grow at the same rate. Hair loss occur when this balance between normal rate of hair fall and new hair growth is disturbed, i.e. If hair fall occur more than 100 hairs a day while new hair growth remain same or new hair growth reduces below normal while hair fall continues at the normal rate (50-100 hairs are shed every day).

The risk factors for hair loss include,

  • Age
  • Family history
  • Mental stress
  • Poor nutrition
  • Medical conditions such as, lupus, diabetes etc.

What are the causes of hair loss?

The exact causes of hair loss is not clearly understood. However, hair loss occurs mainly due to four main causes. They are

  • Hereditary causes that run into family
  • Hormonal problems
  • Medications
  • Medical conditions

Hereditary or family history in hair loss:

This is the most common cause of hair loss. This commonly occurs as male-pattern of baldness or female-pattern of baldness. This occurs gradually and the progress can be predicted. Form men it occurs as receding hairline and for females it occurs as thinning of hairs. Some families may start losing hair at much earlier age than other families. This type of hereditary hair loss can start even as early as puberty time.

Hormonal changes and hair loss:

Hormonal changes and hormonal imbalance can lead to temporary hair loss, for example, during pregnancy and childbirth and around the time of menopause (known as peri-menopause). Thyroid problems can also cause hair loss.

Medications in hair loss:

Various medications are known to cause hair loss. Medications such as anticancer chemotherapy drugs are notorious for causing complete loss of hair from scalp. Other drugs that can lead to hair lossĀ  are, excessive intake of vitamin A (as seen among Eskimos who eat liver of polar bears or various sea animals), arthritis medications, heart medications, birth control pills, drugs used for depression, antihypertensive drugs etc. However, this type of hair loss due to medication usually reverses on stopping the medication and hair regrows to normal level.

Medical conditions and hair loss:

Various medical conditions can cause hair loss, such as

  • Infection of scalp by fungus (ringworm), can cause patchy hair loss. Treatment of the infection reverses the condition.
  • When immune system of body attack hair follicles, it lead to hair loss, a condition known as alopecia areata. It leads to smooth round bald patches in the body.
  • Various skin conditions can cause hair loss, such as lupus, sarcoidosis, lichen planus etc. They lead to permanent hair loss and scarring.
  • A medical (mental) condition known as tricholithomania lead to hair loss. In this condition, the sufferer has uncontrolled/irresistible urge to pull their hairs.

Other causes of hair loss include,

  • Radiotherapy at the head/scalp can cause hair loss. The lost hair may not grow back to previous normal level after treatment is stopped.
  • Excess use of different hairstyle can also lead to hair loss. If scarring is there because of hairstyle, it may lead to permanent hair loss.


Image courtesy of [David Castillo Dominici] at

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