Electrolysis, Photoepilation

The four phases of the hair cycle


There are many influence factors that can affect the hair cycle such as age, heredity, hormones, medication, nutrition and even stress. Nevertheless, we all share the same hair cycle, broken down into four phases: anagen, catagen, telogen and exogen.


This is the hair cycle’s growth phase and it is influenced by the condition of the dermal papilla, which is voluminous and made up of a vascular core. The hair being rich in melanin and hydration, this phase is the target of electroepilation and photoepilation treatments.

The length of the hair varies depending on the body region, age, sex and the individual person. With an anagen phase of 2 to 6 years, hairs can reach a length of 1.28 meters (approximately 4 feet). The anagen phase varies from 1 to 12 months for certain regions of the body, which means hair in these areas can grow from 1 to 6 cm (approximately 0.4 to 2.3 inches).

Area Hair Eyebrows Upper lip Chin Underarms Arms Bikini Legs
Duration of the anagen phase 2-6 years 1-2 months 4 months 1 year 4 months 2-4 months 2-4 months 4 months


It is a transitional phase during which hairs stop growing, but remain attached to the dermal papilla. At this point, melanin is also no longer produced in the germinative zone. The catagen phase is the shortest and generally doesn’t last more than two or three weeks.


This resting phase, during which cells are inactive, involves no growth of the hair shaft. Papilla atrophy occurs and the hair is ready to fall and be replaced by a new anagen hair, after the beginning of the next growth cycle. Moreover, the telogen hair being less pigmented and having a white bulb, photoepilation results are not satisfying in this phase.

About 50 to 100 telogen hairs are normally shed each day, accounting for the hairs you see in the shower and when styling your hair.


This last phase represents the hair expulsion process. During a photoepilation treatment, the complete expulsion can take between 6 to 21 days. Once the hair has fallen, its bulb is no longer visible.

It is important to remember that the hair phase greatly influences the efficiency of hair removal. This is in fact why it is paramount to respect a strict appointment calendar: assiduity will ensure the best results!

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  • Reply Josefa Reina 2017-10-12 at 06:36

    “It is important to remember that the hair phase greatly influences the efficiency of hair removal.”
    Hi Dectro’s team,

    I understand that the hair phase is a critical aspect in a photoepilation treatment, but in your opinion, is it relevant in an electrolysis treatment?

    • Reply Jessica Gagnon 2017-10-16 at 11:42

      Hello Josefa,

      Here is the answer provided by one of our trainer, Marie-Pier Brousseau:
      The hair phase is also very important in electroepilation. In the anagen phase, the papilla is still linked to the blood capillaries, hence making the destruction much more effective than in any other phase. Moreover, the moisture level of the follicle is paramount in electroepilation and the anagen phase presents the best hydration out of all the phases. When working with Blend, the water content will help create caustic soda whereas when working with Thermolysis, the water conducts current.

  • Reply JULIETH HERNANDEZ 2017-12-13 at 07:35


    Taking into account the answer provided by the Trainer, that means less effectiveness in Telogen, catagen phase or not effectiveness in those phases? It’s curious because some cases are presented by professional electrologists that work on virgin hair (80% telogen or untouched areas for at least 4-6 months) applying the “clear & wait” technique and the results after 3 or 4 months of the first clearance are amazing (less than 20% of regrowth). Could you please give us a deeper explanation about this? thanks!

    • Reply Jessica Gagnon 2017-12-21 at 16:24

      Hello Mrs. Hernandez,

      Here is what she responds:
      What should be understood is not that there is no effect at all, but that there’s less. The anagen phase definitely offers the best results, but by respecting the right insertion depth with the right phase, you can still manage to get good results in any phase. It is necessary to consider the germinative cells distribution in the bulb and bulge, and how they will be destroyed with electroepilation.

      Best regards,

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