Hair emerges from hair follicles, at around 100,000 to 150,000 on every head. The hair life cycle includes three phases:

• The anagen phase: this is the growth phase. It lasts for 3 to 6 years. Hair grows.
• The catagen phase: this is the resting phase. Hair stops growing. This lasts for 3 weeks.
• The telogen phase: the falling out phase. The hair falls out and is replaced by a new hair in the anagen phase. This lasts 3 months.

Hair loss can be occasional or chronic.

• Occasional hair loss < than 6 months - also known as diffuse or isolated hair loss

Stress, climate changes, hormonal disruption, dietary regimens, pollution, etc. are all possible factors that could affect the hair. Hair becomes weakened, devitalized and noticeably falls out. Even though this is a transitory occurrence, it's better to react quickly at the first signs.

• Chronic hair loss >than 6 months also known as regular hair loss

The hair follicles' activity determines hair growth. In chronic hair loss, each cycle is shorter than the previous one. After around 25 cycles, the hair follicles are worn out. They resorb and then disappear, sometimes years in advance.
The cause for this type of hair loss is mainly genetic. It is important to adapt the treatment to stop the phenomenon and strengthen the hair. Certain diseases can also cause chronic hair loss.

Effluvium is excessive hair loss.
Alopecia is the lack of hair growth on the head;