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Hair loss

This page aims to give you a general overview of hair disorders.

Hair loss is often a source of anxiety and, although more common among men, it can also affect some women. It can take different forms and be caused by a multitude of factors. To treat it effectively, early intervention is essential.

Hair constantly renews itself and it is perfectly normal to lose a little each day, and more during spring or autumn. It is also natural for hair to get lighter as we age: progressively, the new hairs become finer than the previous.

Hair loss becomes a problem when more than about a hundred hairs are lost each day. In the long term, this can lead to the hair thinning or disappearing completely, which causes a change in physical appearance that is sometimes difficult to live with.

The different forms of hair loss

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Androgenic alopecia
The most common cause of hair loss is androgenic alopecia, meaning its origin is both hormonal and genetic. It is much more common among men – 1 in 2 men is affected at age 50(1)(2) – and it can sometimes start as early as puberty. The hair starts to thin above the temples and forehead first. In women, the hair becomes thinner on the top of the scalp.
Androgenic alopecia is due to increased sensitivity of the hair follicles to androgens. These male hormones accelerate the life cycle of the hair, which gradually wears out the hair follicles. These eventually stop producing and the hair gets thinner.
For more information about androgenic alopecia, please see the expert advice page devoted to the topic.

(1) – Mounsey AL, Reed SW. Am Fam Physician. 2009 ; 80(4): 356-362.
(2) – Matard B et Reygagne P. Thérapeutique Dermatologique. Flammarion Médecine Sciences 2001.

Patchy alopecia on a normal scalp
In this case, there is hair thinning or baldness on certain parts of the scalp, but the rest of the hair is normal and the scalp is healthy. Alopecia areata (an autoimmune disease which causes total hair loss on small areas of the scalp) and trichotillomania (a nervous tic which consists in pulling out or twisting one’s hair) are the two main causes of this type of alopecia.
Putting hair up in tight hairdos such as buns, plaits or ponytails too often can also lead to patchy alopecia. This is a common occurrence among people with frizzy hair.
For more information about patchy alopecia, please see the expert advice page devoted to the topic.

Patchy alopecia on a damaged scalp
Some diseases or skin infections (lichen planus, lupus, etc.), as well as scars due to blows or burns, can lead to the destruction of the hair follicles in the affected areas. These are then completely bald. It is important to distinguish between these two origins quickly: inflammatory diseases (lichen planus and lupus) can cause irreversible hair loss if not diagnosed in time.
Ringworm, a fungal infection of the scalp, also produces patchy alopecia. It is particularly common in children. In most cases, the hair grows back once the infection has cleared.

Telogen effluvium
Telogen effluvium is characterised by sudden, abundant and diffuse hair loss and can be triggered by physiological factors (nutritional deficiencies, extreme fatigue, childbirth, the stress of surgery, etc.) or psychological factors (emotional shock, intense stress, depression). It is generally harmless and in most cases it resolves itself spontaneously after a few months.
For more information about telogen effluvium, please see the expert advice page devoted to the topic.

Treating hair loss

Taking action as early as possible is essential to avoid baldness: treatments are much more effective if the hair has not completely disappeared. Consequently, you should see your skin specialist as soon as you notice that your hair has started thinning. They will help you determine the cause of your hair loss and decide on an appropriate treatment: treatments applied locally, oral medication, or even surgery in the most severe cases.
For more information on preventing and treating hair loss, please see the expert advice page devoted to the topic.