If you are a patient of laser hair removal, you know that multiple sessions are required.
Each session treats 5 – 10% of hair only. We try our very best to get as close to 80-90%. However, it is important to keep in mind that it is impossible to reach 100%. Our bodies really like to produce new hair every year!
Only about 5-10% of hair is affected by the laser on any given treatment. The reasons are quite easy to understand. The primary goal of laser hair removal is not to zap the hair but to zap the blood capillary that is feeding the hair growth. The laser detects that color in the hair and shoots a laser. The hair works like an antenna that transmits all that energy to the blood capillary zapping it and scarring it. Only 5-10% of hair has the blood capillary connected to the root.
Is it really permanent?
In short, no. Laser hair removal works by heating the hair follicles to stop new hairs from growing. This puts the hair follicles in a state of dormancy for a long period of time — much longer than with shaving and waxing. When the hairs do grow back, they’ll be lighter, finer, and fewer in number.
Although the procedure is often touted as a form of “permanent” hair removal, laser treatment only reduces the number of unwanted hairs in a given area. It doesn’t get rid of unwanted hairs completely.
Schematic of the hair growth cycle and the factors that may influence a transition from anagen to telogen vs. telogen to anagen phase.
The table below shows an image of all the hair phases and the phase we are looking for is the anagen phase.
The Three Phases of Hair Growth
| Phase | Duration | Activity | LHR Relevance |
| ANAGEN | 2–6 years (scalp) 2–6 weeks (body) | Active growth; follicle fully formed, melanin-rich bulb connected to papilla | TARGET PHASE — laser destroys actively growing, pigmented follicles. Only 10–20% of body hair is in anagen at any time |
| CATAGEN | 2–3 weeks | Transitional; follicle shrinks, melanin production ceases | Poor response — less melanin, follicle detaching from blood supply |
| TELOGEN | 3–4 months | Resting phase; hair sheds, follicle dormant | No response — no active melanin target in follicle |
Why follow-up sessions are needed
Follow-up treatments are necessary to get the most out of laser hair removal. The exact number of maintenance laser treatments varies by individual. According to the Mayo Clinic, most people need between four and six laser therapy sessions.
You also need to space these out by six weeks each — this means that the full treatment cycle can take up to nine months.
After each session, you’ll likely notice fewer hairs. Any hair that remains or regenerates will also be lighter in both texture and color. The AAD estimates that the number of hairs will reduce by 10 to 25 percent after your initial session. The rate of reduction thereafter will improve, but will also vary.
Additionally, for the best results, you’ll likely need occasional maintenance sessions. These help ensure that the hair follicles don’t regenerate. Depending on your individual needs, you may need a maintenance session once or twice a year after your full initial round of laser treatment.
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