What illnesses are linked to hair loss?

Although hair loss is often associated with aesthetic problems and low self-esteem, it can also be a sign of more serious underlying conditions. Underlying causes can range from autoimmune disorders, such as alopecia areata, to scalp infections, to systemic conditions such as thyroid disorders. Discover which illnesses can cause hair loss and all our advice on how to reverse the process.

Hair diseases: what are they?

Androgenetic alopecia is the best-known and most frequent form of hair disorder, but androgenetic alopecia is not a disease. There are also diseases that can affect the hair. These diseases, whether caused by hormonal imbalances, infections, autoimmune disorders or other factors, can lead to hair loss, changes in texture or other scalp abnormalities.

Androgenetic alopecia

Androgenetic alopecia is the most common form of hair loss in individuals, affecting both men and women, although it manifests itself differently between the sexes.

One of the first and most recognisable manifestations of male pattern baldness is the receding hairline at the temples. Over time, this hairline may continue to recede, leaving the forehead increasingly bare. After or in parallel with the receding hairline, hair loss often continues to manifest itself as a thinning or bald area at the top of the head. This area may gradually widen. In the most advanced cases, the loss may continue until only the hair on the sides and back of the head remains, forming a sort of crown.

Unlike male alopecia, female baldness manifests itself as a diffuse thinning over the entire scalp. The hair becomes thinner and less abundant, with no obvious bald spots. It is also common to see an area of increased sparseness at the crown of the head, particularly along the central parting.

Androgenetic alopecia is the result of a complex combination of genetic and hormonal influences that disrupt the natural hair cycle. This cycle, which governs hair growth, rest and loss, is divided into three major phases. The first, the anagen phase, is the phase of active hair growth, which can last from 2 to 6 years. Next comes the catagen phase, a brief transitional phase of 2 to 3 weeks during which the hair stops growing. Finally, the telogen phase, lasting 2 to 3 months, is the period of rest before the hair falls out, making way for new hair.

The main cause of androgenetic alopecia is the hormone dihydrotestosterone (DHT). This hormone derived from testosterone specifically targets hair follicles, particularly in genetically predisposed individuals. Under the effect of DHT, the hair cycle is disrupted. The anagen phase is shortened, leading to reduced growth duration. At the same time, the follicles themselves undergo miniaturisation, producing progressively thinner and shorter hair. Over time, the combination of the reduced duration of the growth phase and the miniaturisation of the follicle gives the appearance of a thinning scalp.

Alopecia areata

Alopecia areataalso known as alopecia areata, is an autoimmune condition that manifests itself as sudden hair loss in circular patches. Usually located on the scalp, they can affect any hair-bearing area of the body.

This hair loss condition is the result of the immune system attacking the hair follicles. This autoimmune reaction can be triggered or exacerbated by various factors, such as stress, infections, genetic factors or even hormonal changes.

The course of alopecia is unpredictable. Some people may experience complete regrowth within a few months, while others may experience recurrent episodes of hair loss or even progression to total hair loss on the scalp (alopecia totalis) or all over the body (alopecia universalis).

Corticosteroids, administered locally or by injection, are commonly used to stimulate hair regrowth.

Scarring alopecia

Scarring alopecia is a form of hair loss in which hair loss is accompanied by scarring of the scalp. It is due to irreversible destruction of the hair follicles, which are replaced by scar tissue. Unlike other types of alopecia, such as androgenetic alopecia or alopecia pelada, scarring alopecia causes permanent hair loss.

Symptoms of scarring alopecia include bald areas with smooth skin and no visible follicles, sometimes accompanied by redness, inflammation or itching.

If hair loss due to this disease is permanent, solutions such as hair transplants can be considered once the condition has stabilised.

Telogen effluvium

Telogen effluvium is a temporary problem hair loss resulting from changes in the normal hair growth cycle. Under normal conditions, only 5 to 10% of a person's hair is in the telogen phase at any given time. However, in the case of telogen effluvium, this percentage increases considerably, leading to abnormal hair loss.

Telogen effluvium can be triggered by a variety of events or situations, in particular :

  • A major emotional or physical shock, such as surgery, serious illness or childbirth.
  • Poor nutrition or vitamin imbalance, such as iron deficiency.
  • Certain drugs, particularly those used to treat high blood pressure, depression or cancer chemotherapy.
  • Hormonal changes, such as those associated with the menopause.
  • Scalp diseases such as dermatitis.

Although worrying and psychologically distressing, telogen effluvium is generally reversible. Once the underlying cause has been identified and treated, hair usually starts to grow back within 3 to 6 months.


Ringworm is a skin and hair condition caused by fungi known as dermatophytes. It is actually a specific form of mycosis. 

Contagious, it can be spread by direct contact with an infected person or indirectly via infected personal objects or animals. Ringworm is characterised by circular bald patches where the hair appears to be broken off on the surface of the skin. These areas may appear red, scaly and itchy. In addition, small pustules or pimples may emerge around these areas.

Flat lichen

Follicular lichen planus, also known as lichen planus pilaris, is the most common type of lichen. an inflammatory condition which targets the scalp, mainly affecting young women. The disease progresses in phases, alternating between periods of activity and remission. It is characterised by irreversible hair loss in the affected areas. Treatment is based on the use of corticosteroids, either applied locally or administered orally.

Hair loss: a sign of illness?

Hair loss, although common and often associated with ageing or genetic factors, can also be an indicator of certain underlying diseases or disorders. 

In some cases, excessive hair loss can mean that the body is reacting to an imbalance, stress or condition. For example, conditions such as thyroiditis, iron-deficiency anaemia, lupus or syphilis can lead to hair loss. 

In addition, eating disorders such as anorexia or bulimia, which lead to nutritional deficiencies, can also cause hair loss. Hormonal imbalances, particularly in women (such as polycystic ovary syndrome), may also be to blame.

What to do about hair loss

What hair loss Whether linked to hereditary factors, hormonal changes, medical conditions or even stress, it's natural to feel concerned. Arming yourself with knowledge, understanding the potential causes and exploring the various solutions is essential if you are to tackle hair loss effectively and find suitable treatments.

Carry out a diagnosis without delay

Hair loss can be a sign of many health problems, from nutritional deficiencies to autoimmune diseases. When faced with abnormal or unexpected hair loss, it's vital not to remain passive and to rapidly seek a diagnosis precise.

Renowned as one of the best in his field, Centre Clauderer specialises in the precise identification of the underlying causes of hair loss and other hair problems. 

Thanks to a team of highly qualified professionals and state-of-the-art equipment, the Centre Clauderer is able to offer a wide range of services. diagnosis live in Paris or remotely.

Adopting the right gestures

To combat hair loss effectively, you need to take simple but essential steps on a daily basis. It's essential to choose shampoos and hair care products that are suited to your hair type and gentle on the scalp. Avoid hairstyles that are too tight and pull on the roots, such as ponytails or braids. 

Finally, eat a balanced diet rich in vitamins and minerals, because good nutrition is the key to healthy, strong hair. These simple habits can go a long way to preventing and limiting hair loss.

Jean-François Cabos

Jean-François Cabos is the creator of a unique hair care method based on the research he coordinated, which led to the publication of the book "Cheveux, Racines de Vie" with Hélène Clauderer by Robert Laffont (Collection "Réponses/ Santé").

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