Permanent hair removal uses wavelengths that are absorbed by the black color, in this case by melanin in the human body.

Melanin is found on the skin, in lentigines, ephelides and nevi, but also under the skin in black hairs and the dermis.

The laser hair removal process

When the laser specialist presses the trigger on the handpiece, a laser shot is delivered.

On impact with the skin’s surface, a depilatory laser will be absorbed by anything black. If you have white skin and black hair, the hair absorbs the laser energy selectively.

Laser energy is then guided through the hair shaft to the hair bulb and dermal papilla. The bulb can be considered the hair production factory.

The intense heat reaching the bulb will destroy the plant by selective photothermolysis.

This hair will never grow back.

So, you may ask, what happens if the skin is black or tanned?

That’s a very good question, so we’ll use a laser that’s less specific for melanin absorption, and we’ll bet on the concentration of melanin in the hair so that, despite the skin color, the hair absorbs most of the laser energy while preserving the dermis for selective photothermolysis.

This is why we use Alexandrite or Diode lasers on fair skin with hair that is sometimes a little lighter, but the laser is very specific for melanin.

And we use a Yag laser for darker skin types with thick, black hairs, very rich in melanin, but a laser with less specificity for melanin.

This is where the doctor’s expertise comes into play, for a precise clinical analysis of phototype and hair type, and therefore of the laser to be used and the parameters to be adopted to obtain a safe and effective treatment.

During the consultation, I explain to each patient how the laser works, the phenomenon of melanin in the hair and in the skin, and the impact of tanning on the safety and effectiveness of treatments, so that I can carry out a treatment under the right conditions.

I often tell patients that a well-managed laser hair removal treatment requires a good understanding between the operator and the patient, and this in turn requires a good understanding of the treatment to be delivered.

Some say that laser hair removal was above all vascular destruction

No, laser hair removal is selective photo thermolysis with melanin as the chromophore.

But it’s true that the absorption of energy, and therefore the increase in temperature of the hair shaft, destroys the bulb of the hair papilla, and also cauterizes the capillaries that feed the papilla. So this is an accessory phenomenon linked to the rise in temperature, but not a selective vascular photothermolysis with a red target chromophore.

On darker skins, the phenomenon is a little more pronounced, as Nd-YAG has less absorption in melanin and goes deeper, even if the main phenomenon remains selective photothermolysis linked to melanin, there is also photocoagulation of the vessels in the hair’s dermal papilla.

So, if you want effective laser hair removal, you need to :

• A good aesthetic doctor, well trained in medical lasers, who knows how to analyze your skin type, your hair type and how it evolves over the course of the year.
• Excellent technical facilities, with powerful depilatory lasers covering all phototypes.
• A good treatment protocol, neither too many sessions nor too few, just what the scientific literature tells us.

The right laser hair removal protocol

The life of hair

To get the basics right, let’s talk about the life of the hair.

Hair lives and dies.

The phases in the life of the hair are as follows:

• The anagen phase is the hair’s growth phase. The hair grows through the dermis from the papilla and stabilizes as a full-grown hair.

• In the catagen phase, growth is complete, the hair retracts, the follicle diminishes in size and becomes less sensitive to the laser, detaching from the bulb. It remains embedded in the dermis.

• In the telogen phase, the hair is gradually expelled, falling out and being replaced by new hair in the anagen phase.

On average, we lose between 100 and 150 terminal hairs every day. Mostly hair, but obviously also on body parts, bikini line, underarms and legs.

So, if you’ve understood how selective photo thermolysis works, you intuitively understand that only hair in the anagen phase will allow bulbs to be destroyed and permanent hair removal to be achieved.

However, the percentage of hairs in the anagen phase at any given moment on our bodies is reduced by 15-20%, according to various studies.

This is why repeated sessions are needed to “ catch” hairs in the anagen phase. If between 10 and 15% of hairs are treated per session, 8 sessions are needed to achieve a complete result.

The interval between sessions is a compromise, as the phases of hair growth are not the same for each area. But the important thing is to have regular intervals, so that a certain number of hairs that have entered the anagen phase can be treated each time.

What’s more, if treatment is performed at regular intervals, the intense heat diffused into the bulbar areas produces an overall slowdown in growth, with finer hairs and a certain synchronization of hair growth making sessions more effective as the treatment progresses.

Patients often experience late regrowth after 3 or 4 sessions, and then suddenly feel that everything is growing back. In reality, hair growth has synchronized with the previous sessions. Hairs are more numerous in the anagen phase at this time, and these sessions are crucial to the effectiveness of the treatment.

Hence the impact of summer breaks when patients go sunbathing. It’s important to explain to patients the consequences of a summer break. In general, this can mean a few extra sessions to achieve a perfect result.

To shave or not to shave before treatment?

“Obviously shave; and freshly, the day before, the morning of, or just before the session.”

In fact, the outer part of the hair that we see and touch is of no interest in laser hair removal, since it is the subcutaneous hair shaft that directs the energy to the bulb and papilla.

Worse still, the visible hair still absorbs energy, creating a loss of effectiveness. What’s more, the hair pressed down by the laser head and heated to over 60° leaves small brown traces visible on the surface of the skin. In short, laser hair removal requires shaving before treatment.

Shave or wax?

If you’ve understood correctly, we want to treat hairs in the anagen phase at each session. A certain percentage of these hairs will be affected by selective photo thermolysis. If, between sessions, you pluck the hairs with wax or a depilatory machine, you’re not allowing the hair cycle to take its course, so you’re preventing the hairs from reaching the anagen phase and being able to be candidates for the famous selective photothermolysis.

It is therefore essential, once laser hair removal treatment has begun, to only shave between sessions. However, you can shave as much as you like between sessions.

Terminal hair versus down

Terminal hairs are thick, deeply embedded in the dermis, generally rich in melanin, and naturally found in androgenic areas (beard, armpit, bikini line and legs).

Down, on the other hand, is fine hair with little or no melanin, more superficial, in the dermis and present on non-androgenic areas and in children.

It’s very important to distinguish between these 2 types of hair, as laser hair removal for down is contraindicated.

Treating down exposes the patient to the risk of paradoxical stimulation.

As downy hair does not absorb melanin, there is no selective photothermolysis. Instead, the laser heats the skin, creating inflammation. This inflammation will send a stimulating message to the bulb of the downy hair, which will then become fuller, even transforming into terminal hair.

I should add that laser hair removal requires shaving beforehand, which can de facto stimulate downy hair in the same way as waxing.

In short: never touch down. In spite of this, we often see young patients who have started to pluck the down that has turned into terminal hair. Here again, the doctor’s expertise comes into its own.

The doctor will weigh the benefit against the risk of paradoxical stimulation.

If “the damage has been done”, we can engage in treatment on stimulated downy areas to improve the patient’s daily life.

The patient must be made aware of the possibility of long-term laser treatments.

Is it really permanent hair removal?

Yes, hair removal can be considered permanent. Every hair that has undergone selective photothermolysis in the anagen phase will never grow back.

That’s in theory, if patients had no hormonal variations and if hair production was stable and mature throughout life. But this is obviously not the case.

Two main factors can lead to regrowth and therefore require maintenance with laser hair removal.

Hormonal variations:

In women, puberty, taking or stopping contraception, pregnancy and breastfeeding, as well as any sub-clinical hormonal variations that cannot be detected, can induce the production of new hair follicles that did not exist during the year of laser hair removal treatment.

As a result, regrowth can appear in areas where there was nothing for some time. It is then necessary to make another appointment for so-called maintenance sessions.

Physiological hair maturity :

In women, studies suggest that hair maturity peaks around the age of 30.

From puberty to age 30, hair production, melanogenesis and sebaceous production all increase. Once this peak is reached, production is stable, then decreases until the menopause.

So after age 30, following a well-managed treatment, there’s a better chance of achieving permanent laser hair removal with less maintenance.

That said, a large proportion of my patients come around the age of 20.

In fact, even if hair maturity occurs a little later, the benefits of starting early are far greater than if you wait until 15 to 20 years after puberty.

What’s more, we can’t predict future hormonal variations or the exact age of hair maturity.

In short, it’s best to start your depilatory treatment early, after puberty, to get the longest-lasting benefits, even if it means doing a few maintenance sessions.

Speaking of investment, is laser hair removal really expensive?

With laser hair removal, all costs are concentrated over one year. It’s certainly a major initial investment, but it’s still much cheaper than a lifetime of hair removal at an institute or even at home. Not to mention the abysmal time savings.

Of course, it’s crucial to choose the right clinic and doctor to supervise your treatment, so that the settings and evaluation of hair and skin give the best and safest results.