Causes of hair loss

Every second man is affected by hair loss. But what causes it and how do you recognise hair loss? You can find out more about the symptoms and causes of hair loss here.

Symptoms of hair loss

The symptoms of hair loss can vary widely:

  • Bald patches develop above the receding temples
  • Less hair grows and the hair becomes thinner overall.
  • The volume of the hair is reduced
  • The hairline begins to recede
  • Bald patches develop on the back of the head
  • The hairline recedes
  • A "tonsure" develops on the rear section of the back of the head

In many cases, hair loss and balding in men follows a particular pattern. The Hamilton-Norwood scale, for example, defines various types and stages of hair loss. In men, hair loss often begins at the temples and on the brow. As it progresses, the hair becomes thinner on the back of the head and then over the entire scalp.

Hamilton-Norwood scale from stage 2 to 5

The growth cycle of hair

The growth cycle of hair is divided into three phases. The hair is produced in the active (anagen) phase. This process can take between two and six years. The transition (catagen) phase takes a few weeks. During this period, the follicle loosens and falls out. Next, the follicle regenerates in the resting (telogen) phase. This phase can take between two and six months. Then the process begins again and the hair root produces a new hair. However, this cycle does not go on indefinitely – a hair regenerates itself approximately 14 times before the hair root dies off completely. There are various types of hair loss that lead to hair falling out prematurely or to the interruption of the growth cycle.

Alpecin hair growth cycle

Hereditary hair loss (androgenetic alopecia)

In men, an excess of testosterone sets in during puberty. This encourages the growth of facial hair, but the excessive testosterone has a negative effect on hair roots. They are overly sensitive to dihydrotestosterone (DHT). If the person has the corresponding hereditary disposition, DHT inhibits the formation of the secondary messenger compound, cAMP, which is responsible for metabolism in the hair root. This shortens the growth phases, resulting in hair loss.

In many cases, the first sign of hereditary baldness is thin hair at the temples. In time, this can result in a receding hairline. Thinning hair on the back of the head is also an indication of androgenetic alopecia. Often, all that is needed to assess the personal risk of developing baldness is a look at the family photo album – because hair loss can be inherited from either the mother or the father. And if you want to be absolutely certain, you can calculate your personal risk with our baldness calculator.

Stress-related hair loss

Physical stress, particularly competitive sports, lack of sleep and shift work, can also lead to hair loss. Stress at work or family problems are also hard on the mental state and cause stress. If this continues at a high level for several weeks or months, it takes its toll on the body.

Due to stress – for example due to strenuous sporting activities, excessive fitness workouts or competitive sports – the energy requirements of the human body increase. Therefore, the energy no longer gets to the hair roots, because it is required in other parts of the body. As a result, the hair roots no longer receive an adequate supply of nutrients. Possible long-term effects: thinning hair and hair loss.

Both hereditary and stress-related hair loss can be prevented. We will now describe two further types of hair loss. These types of hair loss are medical problems that need to be treated by a medical practitioner:

Diffuse hair loss

Diffuse hair loss is very common. Unlike hereditary hair loss, in diffuse hair loss, the hair thins out generally and it does not follow any typical pattern. The loss of hair is not limited to any specific parts of the scalp (the back of the head or the forehead) – the hair falls out uniformly, all over the scalp.

There are several different causes of diffuse hair loss: physical or mental stress, medicines or diseases. In all cases, the roots of the hair are not supplied with sufficient nutrients and energy, because both are needed by other parts of the body. As a result of this lack of energy, the hair falls out and becomes thinner.

Alopecia areata

Alopecia areata is a relatively rare form of hair loss. Round or oval bald patches suddenly form on the scalp, the eyebrows or the beard area. The size of the bald patches varies. Another typical characteristic of alopecia areata is the so-called "exclamation mark hairs": hairs located at the edges of the bald patches that get thinner towards the tips and can be pulled out easily.

The causes of alopecia areata are still not fully understood. Scientists suspect that it is triggered by an autoimmune disease. But a hereditary origin cannot be excluded at this time. In most cases, the bald patches disappear without treatment after some time – but it is possible that the symptoms will recur at some point in the future.