How does laser hair removal work?

The principle behind both IPL and laser hair removal is actually the same. They both produce light energy, which the dark pigment in your hair and hair root absorbs. This heats up the hair causing damage to the hair follicle. The hair then shuts down and enters a resting phase. So you see slower growth and, eventually, many fewer hairs growing; this is referred to as hair reduction.

How does laser hair removal work: The science bit

This science behind this is selective photothermolysis.

Photo: the absorption of light photons in pigments (e.g. melanin)
Thermo: The transformation of absorbed light into heat
Lysis: The destruction of the target cells by high temperature

The dark pigment in your hair is called melanin. But you also have melanin in your skin that you want to leave untouched, so the devices are calibrated to hone in on the more concentrated melanin in the hair bulb. This is how it is selective.

The differences between IPL and laser hair removal

So how are they different? It’s in the way the technology works and how the light behaves in each.

IPL Laser
Intense pulse light is a quick flash of multi-spectrum (many colours) non-coherent light. It’s not a laser. Laser is monochromatic (single colour) coherent light (i.e. where all the peaks and troughs of the waves of light are aligned or ‘synchronous’)
IPL systems output wavelengths between 500 nm and 1200 nm A laser produces a light of a single wavelength e.g. a diode laser at 810 nm.
The light is generated from a xenon lamp, which is directed and filtered to provide a range of useful wavelengths targeting the hair, through a transparent glass block (i.e. quartz or sapphire) onto the skin surface. This light can’t be focussed. A laser can be focussed to a single spot
Melanin has a broad absorption peak of light energy, so it can be targeted by a range of wavelength light, from an IPL flash. Melanin can also be targeted by a single, specific wavelength of light from a laser.
IPL is generally suitable for light to medium skin tones, and when combined with Radio Frequency (RF) it can be used to treat darker skin tones too. There are several IPL devices available for home use. There are various types of laser treatments available; diode is suitable for pale to medium skin tones and Nd:YAG laser was designed for treating darker skin types. Only diode lasers are available for at home treatments.

Simply put, to damage the hair follicle and bring on the resting state, the hair must receive enough heat that lasts for the right amount of time. It’s the power density of the treatment that delivers this:
Wavelength, Spot size / diameter, Fluence (energy density) and pulse duration = power density

So how do we know it works?

We’ve discovered hundreds of applications for lasers since the creation of the first in 1960 by Theodore Maiman. The discovery that lasers worked to remove hair came about in the 1970s, when researchers noticed hair loss as a side effect in other dermatological studies. Interest and research continued to grow and IPL and laser hair removal became available to the public around 20 years ago.

So how do we know it works?

Does laser hair removal work? Clinical studies prove it does

The first clinical studies into IPL and laser hair removal published in the late 1990s. There are now hundreds of studies documenting the safety, side effects and results of many professional grade systems.

PubMed search for clinical trials, reviews and articles specifically addressing ‘laser hair removal’ returns 675 results.

  • The first human study in the results dates to 1996, with several more studies following in 1997.
  • In 1998, a notable 2-year long study investigating the permanency of results was published.
  • There are now hundreds more studies into the efficacy, permanency, safety and side effects.

More recently, in June 2013 and published in Dermatologic Surgery (official publication for American Society for Dermatologic Surgery), ‘Laser hair removal: a review‘ served to appraise the literature to date on laser and IPL hair removal and concluded that:

 “in-office laser hair removal devices effectively provide a durable solution for unwanted hair removal”.

About the clinical studies

The clinical studies themselves used varying parameters such as the device itself, power intensities, differing participant skin and hair colouring, body areas (or sites), number of treatments and intervals between treatments. They then measured the hair-count reduction at intervals after the treatments and recorded any side effects. The studies confirmed hair reduction results, with the amount of hair reduction varying from person to person.

For example, one 2006 clinical study with 232 participants compared the hair reduction results from IPL, Alexandrite and Diode lasers at 6 months after the last treatment. Here are the results:

Alexandrite Diode IPL
Hair reduction % 6 months after last treatment 68.75% 71.71% 66.96%

IPL and laser hair removal today

Although many early machines were rushed to market “without adequate testing of effectiveness”, today we have refined technology and fine-tuned procedures for better results and safety. It’s the knowledge shared from hundreds of clinical studies over the last 20 years that helped to make such improvements.

Advancements continue, and now hundreds of thousands of us enjoy the results of laser hair removal each year, and the popularity continues to grow.

 In 2013, 464,000 laser hair removal treatments were performed by members of the American Society for Dermatologic Surgery, a 46% increase over 2012.

In 2013, 464,000 laser hair removal treatments were performed by members of the American Society for Dermatologic Surgery, a 46% increase over 2012. Source: American Society for Dermatologic Surgery


“First introduced in the mid-1990’s, laser hair removal has become an accepted treatment modality for patients seeking to reduce unwanted hair and has been found to improve quality of life for many patients. Lasers currently in use for hair removal include the normal-mode ruby, normal-mode alexandrite, diode, and neodymium: yttrium-aluminum-garnet (Nd:YAG) lasers, as well as intense pulsed light devices.”
American Society for Laser Medicine and Surgery

The American Academy of Dermatology website also provides guidance on what to expect following treatments. They say you can expect about 10% to 25% hair growth reduction with each treatment, and the hair that does regrow after tends to be lighter and finer in texture.

So does IPL  and laser hair removal work? Yes.

The benefits of IPL and laser hair removal are very real, but so are the possible side effects.

Read on to learn more.

Possible side effects

It’s important you are aware of the risks associated with treatment too. The known risks and complications associated with clinic-based IPL and laser hair removal are:

  • Eye and vision damage – always wear appropriate eye protection (patient and operator) during clinic treatments
  • Skin injury – scarring, hyperpigmentation (darkening of pigmentation), Hypo and depigmentation (loss of pigment resulting in pale or white areas), Burns and Blisters, Infection, Bruising, Prolonged redness
  • Worsening of pre-existing skin condition/s: Paradoxical hypertrichosis, which is increased hair growth following laser hair reduction procedures. The exact cause remains unknown.

Your clinic should make these risks very clear and give you time to digest and make a decision. Don’t be rushed by limited time discounts or offers.

Choose your provider carefully

It’s important to choose your treatment provider very carefully. In the UK and some states in the US, the procedures are unregulated (this means anyone can provide and operate them). This could be a plastic surgeon, dermatologist nurse or beautician. The possibility of treatment risks becoming real issues is far greater with an untrained and inexperienced operative. The assessment that they make of your skin and hair type, how they set your expectations, approach potential problems and react to complications, are critical to your safety and the treatment’s success. Make sure you choose a provider with great safety standards, best practise, training and experience.

Today we want the same salon results without the salon price tag. And from the comfort of our own home. So it’s not surprising there’s an ever-growing choice of at home devices using adapted technologies. But are home devices just as good?

Read more in this section: About laser and IPL hair removal

  1. What is IPL and laser hair removal?
  2. How does laser hair removal work?
  3. Laser hair removal at home vs professional treatments: which is best?
  4. Is laser hair removal permanent?


Share this Story