What is hair loss?

Hair loss is a common reason for consulting a dermatologist. However, the different types of hair loss (acute or chronic telogen effluvium, androgenetic alopecia or age-induced alopecia) are caused by different malfunctions in the scalp. They therefore require different treatments.

Hair loss and the hair cycle are closely linked

The hair’s growth is cyclical in nature: this phenomenon is referred to as the hair cycle. It is characterized by a series of three distinct phases during which the hair grows, is maintained, regresses and then falls. 
  • The anagen phase is associated with hair growth. During this phase, which lasts two to six years, the dermal papilla cells multiply actively. The hair shaft, which is produced by the hair follicle, grows approximately one centimeter per month. 
  • The catagen phase lasts two to three weeks. During this transition between the anagen and telogen phases, the hair follicle is inactive, and the hair stops growing.
  • The telogen phase involves the elimination of “dead” hair, which is then replaced by new hair. Hair loss occurs when a new anagen phase begins. This stage lasts for two to three months.
In its lifetime, the hair follicle undergoes 25 to 30 cycles on average. Fortunately, the number of hairs that grow is always larger than the number of hairs that fall: a loss of 25 to 60 hairs per day is considered normal by all health professionals. 

Occasional hair loss, chronic hair loss, androgenetic alopecia and age-induced alopecia: very different disorders

Hair loss can vary greatly from one person to another. It is divided into three main categories: Occasional hair loss (acute telogen effluvium and anagen effluvium), chronic hair loss (chronic telogen effluvium, androgenetic alopecia), and age-induced alopecia. 

Acute telogen effluvium

Acute telogen effluvium is the most common type of hair loss in women. It is characterized by an increase in hair loss three to four months after a triggering factor. This is why it is more commonly referred to as “reactional hair loss”. Seasonal hair loss is one example of acute telogen effluvium. 

The hair cycle is disrupted, triggering an abrupt, diffuse and simultaneous loss of hair. The proportion of hairs in the anagen phase shifts to 70% (vs 85% in physiological condition), along with an increase of those in the telogen phase (30% vs less than 10%), and hair loss can reach up to 300 hairs per day, versus the usual 25 to 60 on a normal scalp.  

Stress, a low-calorie diet, postpartum period, post-surgery, changes in season: telogen effluvium is considered acute in these cases. Once the cause of the hair loss is identified and eliminated, hair will begin to grow back after a period of about six months.

Anagen effluvium

Anagen effluvium has a rather quick onset, spanning from a few days to a few weeks. The result is a sudden loss accompanied by often severe diffuse alopecia, potentially spreading to 80% of the hair and affecting men as well as women. 

This type of hair loss is observed primarily following the administration of cancer treatments such as chemotherapy or exposure of the head and/or neck to radiation therapy. 

What is androgenetic alopecia?

Androgenetic alopecia is defined as a chronic hair loss (lasting more than six months) that affects mainly men. These bouts of hair loss eventually lead to a reduction in hair density.

The mechanism by which androgenetic alopecia manifests is hormonal and involves the androgen receptors found in the dermal papilla. These hypersensitive testosterone receptors are stimulated by dihydrotestosterone (active component of testosterone), leading to the miniaturization of the hair follicle. This leads to changes in the hair’s natural cycle by speeding up growth. This action puts strain on the scalp: the hair becomes thin until it stops growing altogether. 

Baldness is an advanced stage of androgenetic hair loss and is the most common form of hair loss in men. Often hereditary, it can begin at a young age, sometimes as young as 20. In this case, localized alopecia is usually observed in certain areas, mainly on the forehead and around the temples.

Our care routines

My anti-occasional female hair loss routine (less than 6 months)

Action against occasional hair loss (caused by stress, fatigue, post-pregnancy, changing seasons, etc.)

Test this routine > My anti-occasional female hair loss routine (less than 6 months) > See my routine >

My anti-chronic female hair loss routine (over 6 months)

Action against chronic hair loss

Test this routine > My anti-chronic female hair loss routine (over 6 months) > See my routine >

My male anti-hair loss routine

Action against chronic hair loss (> 6 months)

Test this routine > My male anti-hair loss routine > See my routine >
See all care routines >