How does laser hair removal destroy hair permanently?

Laser hair removal is based on a simple principle: the light emitted by the laser is absorbed by melanin, the pigment in the hair, which turns it into heat. This heat destroys the cells in the follicle responsible for regrowth, while sparing the surrounding skin as much as possible. A follicle destroyed in this way no longer produces hair. Several sessions are needed, as the laser only acts on hairs in the growth phase, and they are not all in that phase at the same time. At the Centre Laser Valbonne, we mainly use the SUBLIM® Mono laser, a diode laser.

How does laser light target the hair follicle?

This mechanism has a name: selective photothermolysis. The laser emits a single wavelength, chosen to be well absorbed by melanin. The hair, rich in melanin, captures this energy and heats up. The heat then spreads to the stem cells located at the base and along the follicle. When the temperature reached is high enough, these cells are irreversibly destroyed: the follicle can no longer produce hair.

Why does the laser spare the skin around the hair?

Two settings concentrate the effect on the hair. First, the wavelength: it is far more strongly absorbed by the melanin in the hair than by the other components of the skin. Second, the duration of each pulse: it is long enough to heat the follicle, but short enough that the heat does not have time to spread to neighbouring tissue. Cooling the skin during the session completes this protection. That is why the settings must be adapted to each skin and hair type: at the Centre Laser Valbonne, Dr Milène VERA defines them herself at the first session.

Why are several sessions needed?

Each hair follows a cycle: a growth phase (anagen), a short transition, then a resting phase, before falling out. The laser is only effective during the growth phase, when the hair is still connected to the base of the follicle. Resting follicles escape the treatment and will be reached at a later session. That is why a treatment course generally includes 6 to 8 sessions, 6 to 8 weeks apart.

What actually happens during a session?

The laser handpiece is passed over the whole area to be treated, pulse after pulse. The session is short: about 5 minutes for the underarms, 20 minutes for the lower legs. Each pulse gives a feeling of warmth or tingling. After the session, redness and slight swelling around the hairs are normal and usually disappear within 48 hours. The treated hairs then gradually fall out over the following days or weeks.

Frequently asked questions

Is laser hair removal really permanent? A destroyed follicle no longer produces hair. However, new hairs may appear later, particularly under the influence of hormones, and are then treated with a few maintenance sessions. It is therefore more accurate to speak of long-lasting hair reduction. For areas that respond very well to the laser, such as the bikini line and lower legs, the result lasts many years, even decades.

Is it painful? The sensation varies from person to person and from area to area: most often a brief feeling of warmth or tingling. Recent diode lasers include skin cooling, which improves comfort. On the most sensitive areas, such as the bikini line, Dr VERA can prescribe an anaesthetic cream to apply before the session.

Is a consultation needed before starting? Yes. At the Centre Laser Valbonne, a free consultation with Dr Milène VERA is compulsory before the first session. It is used to assess your skin and hair, check for contraindications and define your treatment course.

From what age can laser hair removal be started? Generally from the age of 16. Earlier treatment remains possible on a case-by-case basis, after assessment at the consultation. For a patient under 18, a parent's consent is required.

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