What is Laser Hair Removal Mechanism?

A well-groomed and presentable individual will have a much more lasting impact on his audience as compared to a shabby looking one.

As more and more people are becoming savvy to this fact, they are choosing to opt for permanent solutions to their problems.

One such problem happens to be unwanted hair growth.

A lot of treatments are available for one to choose from like waxing, shaving, plucking, threading etc. but all these are temporary.

A comparatively more effective solution is laser hair removal whose effects last longer as compared to all of these methods.

The following sections of the article briefly elaborate what exactly is laser hair removal and how it works.

What is Laser Hair Removal?

Often, unwanted hair growth is a cause of grievance and this is specially so in the case of women.

One prefers to look presentable and well groomed at all times and therefore, it is necessary to deal with this problem at the grass root level.

There are many temporary solutions available in the market but laser hair removal is the one whose effects last longest.

It has been in the market for 20 years now and pioneering research about it has led to astonishing results when it comes to hair removal.

The image on the right shows what a typical laser machine for hair removal looks like.

A laser is nothing but an optically amplified light ray.

This light is targeted on the problem area and the hair is removed one strand at a time. This procedure successfully damages the root at its tip i.e. the hair follicle. When this happens, the hair that is damaged takes a long time to grow back.

Although, the rate of growth of the hair back depends on the person.

It is also to be noted that the process only works for certain hair types as laser mostly works on the principle of photon absorption.

The texture and the color of the hair are also important and should be taken into consideration.

How does laser removal treatment actually work?

It has already been mentioned that the laser effectively tries to destroy the hair follicle which prevents the growth of hair again or slows down the process and this depends on the person.

However, how does it manage to do this without damaging the skin or without any side effects?

Are there any harmful effects that one should know about? The following section elaborates and answers these questions.

There are three main ways in which the laser is able to destroy the hair follicles.


Thermal damage is done by the excessive heat which is generated as the laser is focused on the hair follicle.

It effectively causes local heating.

The pulse duration is managed so that the value is less than or equal to the thermal relaxation time (which is basically the time taken by an object to cool down) of the follicle to confine the damage spatially.


This is typically the shock wave associated with the laser.

When the laser is focused on the hair and melanin and other components mentioned below absorb the light, it causes the production of shock waves (called photoacoustic waves i.e. the sound waves produced due to the absorption of light) which effectively cause trauma to the hair without disrupting the follicles.


This is the damage caused by the free radicals generated during the procedure.

When a photosensitizer (a molecule that causes a change in the chemical composition of another molecule during a chemical process involving light) is used, it causes the generation of oxygen radicals which cause oxidative cell damage.

It is mainly thermal damage that causes the procedure to prevent the hair from growing back.

While these are the ways in which the laser affects the hair follicle, there are two main mechanisms that outline how the whole process actually works and effectively prevents regrowth or slows it down.

These are selective photothermolysis and destruction of the hair follicles. Both of these primarily rely on the laser’s capability of thermal damage to the follicle without affecting the surrounding skin.

Selective Photothermolysis

The principal mechanism behind the working of the hair removal procedure is the principle of selective photothermolysis (SPTL).

The term, in particular, refers to the absorption of laser light by the tissues of the skin when it is being focused on a targeted region.

The absorption is done by certain pigments of the skin and this happens only on a specific wavelength.

Hemoglobin is the pigment present in the red blood cells (RBCs) of the animals. It carries the oxygen in the body and keeps it in circulation.

Oxyhemoglobin is the pigment formed when the animal respires and the oxygen that is breathed in combines with the hemoglobin.

Melanin is the pigment which gives the skin its color. Along with the skin, it is also found in hair and iris of the eye and is responsible for giving them their color.

These above three components or rather pigments that absorb the laser light are known as chromophores.

The characteristics of these three have been studied in detail and their absorption charts have been drawn.

The purpose of studying these characteristics and making a graph is to design the laser accordingly with the proper wavelength, pulse width etc. so that it causes maximum absorption.

When the parameters are set to the correct values then the hair is removed effectively without causing any damage to the surrounding areas.

According to the principle of SPTL, certain requirements need to be met regarding the specifications of the laser to get the maximum benefits out of it.

When the laser light is focused on the proper region, it is absorbed by the chromophores and leaves the surrounding skin unaffected.

Dark material absorbs heat faster as compared to the skin and hence, only the hair is affected by the heat of the laser as the absorption occurs faster and with more intensity.

The skin does not feel the heat. If the dark-colored melanin is not already present in the hair then it can be introduced artificially for the procedure.

As is clear from the above-mentioned facts, the best combination for the person would be to have dark, coarse hair and light skin.

And although it is said that this is a permanent hair removal procedure, it results only in the reduction of the amount of hair present and can slow down the regrowth but cannot completely remove all the hair from the skin surface.

The follicle is weakened and takes time in maturation to produce new hair.

There are many different types of lasers that are used for this purpose and one can choose the procedure that they feel is the best for them.

The thickness of the hair, the depth of the hair roots and also the hair growth cycle are important factors to be considered when an option for this treatment.

Destruction of follicles

Another mechanism that has been proposed for hair removal is destroying the follicular stem cells.

When the hair follicle is exposed to the heat, it gets damaged and as a result, takes time in growing the hair back again.

The image on the right shows what a hair follicle looks like. The pigments present in the follicle are what causes the hair to grow back.

If the follicle itself were to be destroyed then the regrowth would be impossible or delayed for a long period of time.


It has been noted that more and more people are becoming aware of the benefits of laser hair removal over the other options available.

All other choices offer a temporary solution as compared to laser hair removal.

This procedure was approved by the FDA and since then has gained a lot of popularity with the customers.

Women especially, seek out this procedure as it seems more viable than repeated sessions required with the other available options.

One needs to, however, understand what exactly is occurring when the laser is focused on their skin and the whole process is set to motion.

There are also a lot of other facts to consider and one should definitely consult with a dermatologist to know more details about it.

The mechanism, however, has been explained above and gives an idea about the working of the treatment.

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