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Everyone's hair grows differently, depending on age, weight, metabolism, hormones, ethnicity, medications, and other factors. But all hair goes
through three distinct growth phases:
Active growth phase (called the anagen phase)
, which lasts between 2 and 7 years. During this phase the dermal papilla actively produces
cells which form the hairshaft. In certain areas of the body, such as the scalp, the majority (83%) of the hairs are in this phase. During the Anagen
phase the hair has an abundance of melanin.
Degradation phase (catagen phase)
, which lasts between 10 and 20 days, during which the hair stops growing but is not yet shed. About
3–4% of our body hair is in this phase at any given time. The hair follicle shrinks at this time as the hair is prepared for eviction.
Resting phase (telogen phase)
, which can last for several months, during which the hair falls out and a new hair begins to form.
The hair follicle is not treatable during this time.
Laser treatment is only effective when the hair is in the active growth phase. Hairs or hair follicles in the Degradation or Resting phase need
to progress to the active phase before treatment will be beneficial. Therefore
multiple treatments are required for long term permanent hair reduction.
Also in a single treatment not all of the hair follicles in the active phase will be
destroyed. Some follicles are destroyed, others may be miniaturised into vellus hairs
(light fine hairs), and some enter prolonged dormancy. The initial treatment should
be repeated to take care of active hair follicles that were not effectively treated in the
first session as new hair growth is observed, this will typically be some 3–4 weeks
later depending on where the treatment area is.
Further treatments should be planned at regular intervals to treat hairs that are
coming out of the resting phase and into the active growth phase. Generally, we
recommend 6 treatment sessions over 6 months. Given the number of hair follicles
in the resting phase at any given time this hair re-growth can be significant.
Any follicles without a target hair within will simply grow again and will need to be
treated next time around.
Body Site
Follicle
Density
per square cm
Resting
Phase
Time in
Resting
Place
Active
Growth
Head
350
15%
3 months
83%
Arms
80
18%
5 months
79%
Legs
60
18%
6 months
79%
Beard
500
68%
10 weeks
30%
Upper Lip
350
64%
6 weeks
34%
Armpit
65
28%
3 months
69%
Chest/Back
70
28%
3 months
69%
Pubic
70
25%
3 months
71%
W H Y I S A S E R I E S O F T R E A T M E N T S R E Q U I R E D ?
