Laser technology | principe of laser hair removal
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Laser technology

The principe of laser hair removal

Laser hair removal is never 100% complete. The laser only works on hair in the growth phase (anagen phase). We must therefore wait for all hair goes through this phase to destroy through laser. Usually an average of 5-8 sessions is necessary for the laser hair removal is complete (about 85% of destroyed hair). Thereafter, it is possible to carry out maintenance sessions to pluck a few hairs that have escaped treatment. When the hair follicle is destroyed, the hair does not grow more and this definitively. Some recalcitrant hairs, especially in the case of clear hair, may require additional sessions.

The number of sessions depends on the area treated, the type of hair and skin as well as the patient's age.

The skin is subjected to a warm feeling during laser hair removal. That's why we use a powerful cooling system on new lasers for the best efficiency without burning the skin. A soothing and moisturizing cream is applied late in the session.

For which patients?

This technique requires the presence of melanin (dark pigment) in the hair concerned has no effect on the white hair.

All skin phototypes, whatever the intensity of the color can be plucked.

  • The Alexandrite laser is the laser of reference (speed and efficiency) for hair removal but not forc tanned skin of dark skin.
  • Nd-Yag laser, helps remove hair for dark skin, black and tan.

Hair removal can be performed both on the body (underarms, bikini, legs) on the face (upper lip, chin). However epilation of some areas is associated with a risk of stimulation (converting down terminal hairs) has to be evaluated by the doctor and may lead to inadvisable treatment.

Men are increasingly concerned about excess hair growth: back, chest, neck, shoulders, beard, nose. In general, there should be more sessions than for a woman.

What to expect?

The motivations for permanent hair removal laser are both aesthetic and practical. Laser hair removal is never 100% complete. The laser generally allows a permanent hair removal from 80% to 95% of terminal hairs in the treated area.

The hair does not grow all at the same time and it is impossible to destroy all of the bristles of the area at one time. Treatment thus takes place over several sessions, depending on the different hair cycle according to the treated areas.

What is the duration of treatment?

The number of sessions is variable, depending on skin type, hair type, and depending on the body area to be treated. The average is about 5-8 sessions for the most requested areas: underarms, legs and bikini line. We also know that it usually takes more sessions in younger patients and in men.


There are some cons-indications for laser hair removal but there is one that must be strictly observed: tanning. Indeed tanned skin is loaded in melanin which increases the risk of skin burns. Only the Nd-YAG laser can be used on tanned skin (it is a bit more painful and less effective on light, fine hair).

In practice

Before the treatment:

A test is performed on the area to be treated to optimize the choice of the laser parameters (efficacy and safety).

In case of poorly tolerated by the patient pain:

The laser shot is felt as an elastic blow, with intensity perceived in very different ways from one person to another and according to the waxed area. In case of painful sensation, the application of a local anesthetic cream before the session is proposed. Lasers are also equipped with an anesthesia system very effective cold.

Before each session:

  • Stop any waxing or tweezing at least five weeks before the meeting.
  • Do not apply self-tanner in the 10 days preceding the appointment.
  • Preventing physician sun exposure and any drug intake.
  • Shave hair 1 or 2 days before the meeting.

After the session:

  • The skin stays red 1-2 days.
  • Put a soothing cream for a few days after the meeting and avoid sun exposure during the life of the local reaction.
  • Monitor the intensity and duration of local reaction.
  • Systematic sun protection during the treatment period.

Dark skin, black, Asian

The Yag laser hair removal can practice on the black or Asian darker skin without burning. The Yag laser, unlike the Alexandrite laser used for hair removal clearer skin, is poorly absorbed by the melanin in the skin but sufficiently by the melanin contained in the hair in order to destroy it.

The hairs will fall to 2-3 weeks after the meeting.

Melanin pigment of the hair, absorbs energy from the light beam emitted by the laser. This energy is converted into heat and burns the hair and its bulb. The white hair does not contain melanin can not benefit from laser hair removal. For skin phototype 1-4 Alexandrite laser is used

Melanin is also present in the skin. Tanned skin contains more melanin, and the laser may also burn the skin. Therefore it is highly desirable to treat against tanned skin.

Waxing matt black skin is made with a different type of laser laserYag that is not likely to burn because its wavelength has a low affinity for the skin, while it is very well absorbed by the melanin hair

This type of laser is also present in mediderm centers.