Understanding Hair Loss
Getting to the root causes of hair loss.

Understanding Hair Thinning and Hair Loss

Comprehensive overview covers causes, symptoms and treatments of hair loss. Below is a great amount of information regarding hair loss.

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The Hair Growth Cycle

We are born with all the hair follicles we will ever have. As adults, we have about 100,000 individual strands of hair.

The normal cycle of hair growth lasts for 2 to 3 years. Each hair grows approximately 1 centimeter per month during this phase. About 90 percent of the hair on your scalp is growing at any one time. About 10 percent of the hair on your scalp, at any one time, is in a resting phase. After 3 to 4 months, the resting hair falls out and new hair starts to grow in its place.

It is normal to shed some hair each day as part of this cycle. However, some people may experience excessive (more than normal) hair loss. Hair loss of this type can affect men, women and children. The hair growth cycle has three different phases:

1. Anagen

The Anagen phase is the growing phase or the 'on' phase, which lasts for an average of approximately 1,000 days in the human scalp, but can range from 2 - 6 years. During the Anagen phase, hair cells proliferate rapidly. The hair shaft grows in diameter and the hair reaches maximum length.

2. Catagen

The Catagen phase lasts only 1 - 2 weeks - it's the transitional or regressive phase before the resting phase begins. It's essentially when the hair stops growing.

3. Telogen

The Telogen phase is the final resting stage or 'off' phase, which lasts for about 5 - 6 weeks.

When the old hair is in the Telogen phase, activity in the hair follicle is renewed. A new hair in the Anagen phase develops and forces the old Telogen hair out. This is when hairs are lost and you might notice them in the bath or in your brush or comb. In healthy follicles these hairs will soon be replaced by new hair.

A variety of factors can alter the normal hair growth cycle and cause temporary or permanent hair loss including medication, radiation, chemotherapy, exposure to chemicals, hormonal and nutritional factors, thyroid disease, generalized or local skin disease, and stress. You can read more about the causes of hair loss in our Types of Hair Loss section.

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Hair Loss Facts

  • A number of things can cause excessive hair loss. For example, about 3 or 4 months after an illness or a major surgery, you may suddenly lose a large amount of hair. This hair loss is related to the stress of the illness and is temporary. Hormonal problems may cause hair loss. If your thyroid gland is overactive or underactive, your hair may fall out. This hair loss usually can be helped by treatment thyroid disease. Hair loss may occur if male or female hormones, known as androgens and estrogens, are out of balance. Correcting the hormone imbalance may stop your hair loss.
  • Many women notice hair loss about 3 months after they've had a baby. This loss is also related to hormones. During pregnancy, high levels of certain hormones cause the body to keep hair that would normally fall out. When the hormones return to pre-pregnancy levels, that hair falls out and the normal cycle of growth and loss starts again.
  • Some medicines can cause hair loss. This type of hair loss improves when you stop taking the medicine. Medicines that can cause hair loss include blood thinners (also called anticoagulants), medicines used for gout, high blood pressure or heart problems, vitamin A (if too much is taken), birth control pills and antidepressants.
  • Certain infections can cause hair loss. Fungal infections of the scalp can cause hair loss in children. The infection is easily treated with antifungal medicines.
  • Finally, hair loss may occur as part of an underlying disease, such as lupus or diabetes. Since hair loss may be an early sign of a disease, it is important to find the cause so that it can be treated.

Hair Loss Myths

  • Frequent shampooing contributes to hair loss.
  • Hats and wigs cause hair loss.
  • 100 strokes of the hair brush daily will create healthier hair.
  • Permanent hair loss is caused by perms, colors and other cosmetic treatments.
  • Shaving one's head will cause the hair to grow back thicker.
  • Standing on one's head will cause increased circulation and thereby stimulate hair growth!
  • Dandruff causes permanent hair loss.
  • Hair loss does not occur in the late teens or early twenties.

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Different Types of Hair Loss

Alopecia Areata

Alopecia areata is a condition that causes round patches of hair loss, and can lead to total hair loss and is thought to be an autoimmune condition. This occurs when the immune system mistakenly attacks and destroys healthy body tissue.

Alopecia areata is seen in men, women, and children. A major life event such as an illness, pregnancy, or trauma occurs before the hair loss in some, but not most patients

Forms of alopecia include:

  • Alopecia areata -- patches of hair loss, usually on the scalp, but they also can be in the beard or other areas
  • Alopecia totalis -- complete loss of scalp hair
  • Alopecia universalis -- total loss of all body hair

Studies have shown that Viviscal® proves effective in the treatment of all three types of Alopecia. See our clinical trials section for more information.

Self Induced Hair Loss

Some damage to the hair is self-inflicted sometimes consciously or unconsciously. The two main types of self-induced hair loss are Trichotillomania and Traction Alopecia.


Trichotillomania is self-induced hair loss, which results from the continuous pulling or plucking of the hair. It occurs most commonly among young children, adolescents and women and affects twice as many females as males. The hair is often pulled out in distinct patches on the scalp however, some individuals also pull out eyebrows and eyelashes. The treatment for Trichotillomania often involves counseling or psychiatric help, however in some cases an antidepressant may be prescribed.

Traction Alopecia

Traction alopecia is a form of alopecia, or gradual hair loss, caused primarily by pulling force being applied to the hair.[1]:761[2]:645 This commonly results from the sufferer frequently wearing his/her hair in a particularly tight ponytail, pigtails, or braids. It is also seen occasionally in long-haired people who use barrettes to keep hair out of their faces.

Androgenetic Alopecia

Hair loss resulting in thinning is known as alopecia. When it is related to hormones (androgens) and genetics, it is known as androgenetic alopecia, or more commonly just balding. Male pattern alopecia is characterized by a receding hairline and/or hair loss on the top of the head. A similar type of hair loss in women, female pattern alopecia, results in thinning hair on the vertex (top) of the scalp but is generally less severe than occurs in males. The Norwood-Hamilton Scale (Fig 1.) shows the progressive stages of male pattern hair loss. Left untreated, male pattern hair loss is a condition that usually gets worse.

Telogen Effluvium

Telogen effluvium is a form of nonscarring alopecia characterized by diffuse hair shedding, often with an acute onset. A chronic form with a more insidious onset and a longer duration also exists.[1, 2] Telogen effluvium is a reactive process caused by a metabolic or hormonal stress or by medications. Generally, recovery is spontaneous and occurs within 6 months.

Telogen Effluvium can be caused by the following:

  • Acute Illnesses such as febrile illness, severe infection, major surgery and severe trauma
  • Infections of the scalp
  • Major Surgery/Chronic Illness
  • Severe psychological stress
  • Crash diets/inadequate protein
  • Drugs/Medication of which the most frequency cited are beta-blockers, anticoagulants, retinoids (including excess vitamin A), propylthiouracil (induces hypothyroidism), carbamazepine, and immunizations
  • Heavy Metals such as selenium
  • Hormonal Changes
Hormonal Changes:

There are many reasons for hormonal changes within the body; a lot of these can result in hair loss such as: Hair Loss after Child Birth: It is quite common for some women to experience some hair loss approximately 3 months after childbirth. This hair loss is triggered by the sudden changes in hormone levels. Some statistics suggest that 20 percent of mothers lose hair after childbirth and others suggest a figure closer to 45 percent. Fortunately, in most cases the hair will return to normal 9-12 months after the child's birth.

Many women notice that their hair is thicker and healthier during pregnancy, this is due to the increased levels of hormones estrogen and progesterone, which cause more hairs than normal to remain in the growth phase. When the child is born however, many of the hair follicles that had delayed entering the resting phase suddenly enter the resting phase due to a rapid drop in hormone levels. As a result, these hairs are then shed about 3 months after the birth.

Hair Loss resulting from taking the Birth Control Pill:

Birth control pills affect the hormone levels within the body and these hormone levels can affect hair growth. In some cases, hair thinning may occur due to the male hormones present in some contraceptive pills. This type of hair loss is similar to pattern baldness or Androgenetic Alopecia. However, discontinuation of the pill can result in hair loss similar to that which occurs after childbirth due to the drop in hormone levels.

Hair Loss resulting from Thyroid Gland malfunction:

Generally the first test a doctor or specialist is likely to carry out on a patient who is experiencing hair loss is a thyroid function test, as a thyroid problem may result in hair loss. Two types of thyroid problems can occur and either of these problems can result in hair loss. These conditions are Hypothyroidism (the under production of Thyroxine) and Hyperthyroidism (the over production of Thyroxine).

Hair loss may occur from either hypothyroidism or hyperthyroidism. In some cases hair loss is minimal, however some individuals experience severe hair loss. Fortunately hair loss is usually reversible with proper treatment. If you suspect that you have a problem with your thyroid function then you should visit your doctor.

Infections of the scalp:

Infections such as ringworm can invade the hair and skin of your scalp, leading to hair loss. Once infections are treated, hair generally re-grows.

Major Surgery/Chronic Illness:

The shock involved in a major operation can result in sudden hair loss. Also after micro graft and mini graft surgery where follicles are transplanted on the scalp telogen effluvium almost always occurs. Due to the shock of surgery the hair follicles will fall out within about 3 months after which time new hairs will grow from the transplanted follicles.

Some cancer treatments will cause hair cells to stop dividing. Hairs become thin and break off as they exit the scalp. This occurs one to three weeks after the treatment. Patients can lose up to 90 percent of their scalp hair. The hair will re-grow after treatment ends.

Severe Physiological Stress:

Some people experience telogen effluvium or sudden diffuse hair loss after a traumatic event such as the death of a family member or someone close, an accident, abuse or any other severely traumatic event. These events may trigger hair follicles to enter the resting phase prematurely in which case an increase in the amount of hair shed will be noticed about 3 months after the event. When the stressful situation is over or the body adjusts to it, the hair usually grows back.

Crash Diets/Inadequate Protein:

Some people who go on crash diets that are low in protein, or have severely abnormal eating habits, may develop protein malnutrition. The body will save protein by shifting growing hairs into the resting phase. Massive hair shedding can occur two to three months later. Hair can then be pulled out by the roots fairly easily. This condition can be reversed and prevented by eating the proper amount of protein and, when dieting, maintaining adequate protein intake.


Some prescription drugs may cause temporary hair shedding. Examples include some of the medicines used for the following: gout, arthritis, depression, heart problems, high blood pressure, or blood thinner. High doses of vitamin A may also cause hair shedding. The following is list of some drugs that have been reported to have a side effect of hair loss:

  • Alloppurinol (for the treatment of Gout)
  • Heparin (blood thinner)
  • Coumarin (blood thinner)
  • Clofibrate (Cholesterol lowering drug)
  • Gemfibrozil (Cholesterol lowering drug)

The above drugs are only a few of the drugs that have been reported as contributing towards hair loss. If you suspect that prescription drugs that you are taking are causing hair loss you should discuss this with your doctor.

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