How Does Laser Hair Removal Actually Work?

Lasers have been used for hair removal commercially since the mid 1990's, and their use has steadily grown in popularity among the adult population.

Its efficacy and safety are now generally accepted and various clinical studies have been carried out to provide evidence to support this.

This article aims to provide, in understandable terms, an explanation as to what laser hair removal is, how it actually works and how it has developed technologically through the years to include a broader consumer base.​

What is Laser Hair Removal?

​Laser hair removal is the removal of unwanted hair by a process known as selective photothermalysis.  

Photothermalysis is the term given to the process of exposing the area of treatment to pulses of laser light for the purpose of damaging the follicle containing the hair sufficiently to cause the hair to fall out.

Selective Photothermalysis​

​​Visible and invisible (infrared) light targets dark pigment, known as melanin, which is found in hair and skin and which gives it its colour.

​Particularly high levels of melanin are found around the base of the follicle, and it absorbs the laser light, causing a reaction to produce heat.

It is this heat which causes the damage to the follicle, which in turn has the effect of making the hair fall out, usually 1 - 2 weeks after treatment.

The process of selective photothermalysis matches specific wavelengths of light and pulse duration, depending on the skin type and hair colour of the individual.​

The Hair Follicle​

The hair follicle is the hair producing organ of the skin.

there is a large structure at the base of the follicle called the papilla, which is surrounded by a mass of dividing cells including melanocytes, which produce the melanin.

This is known as the matrix​ and is the target for hair removal laser light.

Hair Growth

​Briefly, hair grows in 3 stages:

  1. The growth stage (known as anagen)
  2. The transitional or end of growth stage (known as catagen)
  3. The resting stage (known as telogen)​

Hairs all over the body are at different stages of growth at any given time.

The length of the growth cycle varies, depending on the part of the body and on individual make-up.  

The table below is indicative and based on averages:​

Body Part



Cycle Duration


3 months

1-2 weeks

10 months


3 months

1-2 weeks

10 months


10 weeks

2-3 weeks

14 months

Upper Lip

6 weeks

2-3 weeks

5 months


3 weeks

2-3 weeks

5 months


3 months

2-3 weeks

8 months


16 weeks

2-3 weeks

10 months


24 weeks

3-6 weeks

11-12 months

Laser hair removal can treat large areas relatively quickly but is only effective on those hairs which are in the actively growing stage whilst the treatment is taking place.

It is for this reason that a number of sessions will be required to achieve the desired results.  It is almost impossible to determine the exact number required in advance of any treatment because there are a number of factors affecting this.

For more information see our in-depth article:  ​How Soon can Results be Seen with Laser Hair Removal

Different Types of Lasers​

There are a numerous laser devices currently used for professional laser hair removal, using several different laser systems, namely; Ruby, Alexandrite, Diode and Nd:YAG.

All of these follow the same principles, the major difference being the way in which the light is delivered and the wavelengths used.​

The unit of measurement use for wavelengths of light and infrared radiation are known as nanometers (nm's) and are equal to ​one billionth of a metre.  Hair removal lasers operate at between 700 - 1400 nm's​

Which type is best will depend on the individual and is largely determined by skin and hair type and colour.

How Laser Hair Removal is Advancing​

​Historically, laser hair removal was only effective for those individuals with white skin and dark hair.

This is partly because those with dark hair have more melanin surrounding the hair follicle for the laser to target.  Also, the contrast between the light skin and dark melanin has the same helpful effect.

As the technology used for laser hair removal has advanced, so has the ability to safely and effectively treat those with dark skin.

The system offering the most advanced technology on the market at this time is the Nd:YAG (neodymium-doped Yttrium Aluminum Garnet) which was specifically developed to treat all skin tones.

The Nd:YAG laser can be used to treat Asians, for whom it is the only safe laser currently available.​

It is still the case, however, that at the moment laser hair removal is not effective for those with fine light, grey or light red hair​ but it is unlikely that this will remain the case in the future.

Laser Hair Removal Regulation​

​The FDA (the US Federation for Drug Administration) regulates laser equipment. Therefore, for peace of mind, it is important to check that the laser device is FDA registered and approved for commercial use.

Regulation surrounding the qualifications of the operator of the equipment is less stringent, and varies from state to state, so thorough research should be carried out.

Note: Despite many claims that Lasers can achieve permanent hair removal, this is not currently endorsed by the FDA.

The FDA has endorsed laser hair removal for permanent hair reduction​.

More Information​

For further information see our in-depth articles:


For the past 12 months, I have been testing and playing with all sorts of hair removal products for Hair Free Life. My goal is to provide the most accurate and up-to-date hair removal consumer information on the internet. When I'm not photographing, reviewing and researching hair removal products I play the drums in a samba band and am a volunteer for the Swindon Lions! Got any questions? Write to us below: