Causes of hair loss

Causes of hair loss

Everyone loses about 100 head hairs per day. If structurally more hair falls out than grow back, or if the hair grow back less fast or less full, hair loss will become visible at some point. Hair loss can be caused by a large number of causes or factors. In people who suffer from hair loss, usually multiple causes are to blame. The main causes of hair loss are described below. If you are unsure about the cause (in women, the cause may be less obvious), consult a physician.

Genetics & Heredity

Baldness and hair loss often run in the family. Of the vast majority of men with hair loss, genetics, heredity, is the main cause.

In this type of hair loss, sensitivity to DHT (dihydrotestosterone) plays a big role. This is a derivative of the hormone testosterone. The hair follicles that produce the hair are affected by prolonged contact with DHT, causing them to start producing hair that is less thick until only very thin hair (vellus) starts growing, which is hardly visible.

Hereditary hair loss in women is much less common than in men, but in 50% of women, genetics play a role in hair loss.

Hereditary hair loss in men only develops into the most advanced stage in seven percent of men, whereby only a wreath of hair is left on the head. If hair loss has reached an advanced stage before age 30, it is likely that it will develop into this stage.

Hereditary hair loss generally falls into a pattern, as shown in the Norwood scale. In women, hereditary hair loss often develops into a diffuse pattern, in which the hair on the top of the head gradually becomes thinner. This pattern is shown on the Ludwig scale.

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Sickness & Health issues

A number of diseases, disorders and health issues can cause hair loss.

The thyroid for example, is of great importance for hair growth. The thyroid regulates the metabolism. If the gland is functioning too fast or too slowly, it can have an effect on the hair growth. Hairs will fall out and the hair will become thinner, or the hairs become brittle and thinner. As soon as the problem with the thyroid is treated, the hair growth should recover.

Anemia can cause hair loss and there are a number of autoimmune diseases which cause hair loss. Eating disorders such as Anorexia and Bulimia Nervosa cause hair loss as well (see the section about nutrition).

Mechanical Cause

Hair loss can also occur due to mechanical causes, external forces on the hair such as braiding, rubber bands and pulling the hair. There are also people who compulsively pull their hair or pull out their hair, also called Trichotillomania. Everything that exerts forces on the hair can cause the hair to break off and fall out including the root.


In some cases, stress can lead to hair loss. It can be a trigger for hair loss in people who are genetically predisposed to it. It can also lead to acute hair loss, also called Telogen Efflivium.

When the body is under stress, due to for example a traumatic experience, disease or deficiency, the severity of hair loss can increase.


Hair loss can sometimes be caused by nutritional problems, such as:

  • poor nutrition and a lack of vitamins (see our blog post about vitamins against hair loss)
  • iron deficiency (anemia)
  • eating disorders such as Anorexia and Bulimia Nervosa.


Many medications can cause hair loss. When a certain medication is prescribed, it is advisable to read the leaflet to see if there is a risk of hair loss. If this is mentioned in the leaflet however, it does not mean your hair will actually fall out. Which medications can cause hair loss? This is a long list, there are dozens, if not hundreds of medications that can cause hair loss.

The most common types of medications that can cause hair loss are:

  • antidepressants
  • steroids
  • birth control pills
  • narcotics
  • malaria medicines
  • chemotherapy and irradiation

The treatment of cancer deserves special attention. It is generally known that people who receive chemotherapy have to deal with hair loss. The same goes for irradiation. In the case of the fight against cancer, suppressing cancer is of course more important than the side effect hair loss.

Does hair loss stop when the use of a certain medication is stopped? In most cases yes, even in the case of chemotherapy or irradiation.

Poor Condition of the Scalp

The condition of the scalp is the determining factor for hair growth. Flaking of the scalp (e.g. ordinary dandruff or psoriasis) and an inflamed scalp can reduce hair growth and eventually lead to hair loss.