How does laser and IPL hair removal work and how many treatments do you need?

Shaving less often, no more hard stubble, and fewer problems with ingrown hairs or irritated skin. These are various reasons to choose IPL or laser hair removal, but ultimately it comes down to the same question: how do you permanently reduce unwanted hair growth?

This works very well for dark and thick hair. Laser and IPL can significantly reduce the amount of hair for an extended period. Furthermore, hairs that grow back after a course of treatment may become finer and grow more slowly.

However, it is not as simple as: six treatments and you're done.

How well a treatment works depends on, among other things, the color and thickness of the hair, the skin type, the body area, hormonal influences, the equipment used, and the settings applied.

An armpit, for example, behaves differently from a lower leg. And dark hairs on a chin require a different assessment than fine downy hairs on a cheek.

For me, therefore, good hair removal does not start with the question of which device is best. First, I want to know. what kind of hair grows there, where that hair grows and in what skin. Only then can you determine whether treatment is worthwhile and which technique is appropriate.

To understand why, we must first know something about the growth cycle of a hair.

Why can't you treat all the hairs at once?

A hair does not grow continuously.

Every hair follicle successively goes through an active growth phase, a short transitional phase, and a resting phase. For IPL and laser hair removal, the first of these is particularly interesting: the anagen phase.

Only a portion of the hairs is in this active growth phase at the same time. Moreover, the percentage varies by body area. On average, for the face, it concerns approximately 20 to 30 percent, at the armpits approximately 30 to 40 percent and on the legs about 20 to 30 percent. The remaining hairs are in the catagen transition phase or the telogen resting phase.

That immediately explains why treatment can never be sufficient.

However, this does not mean that 30 percent anagen hairs automatically equates to 30 percent hair reduction after a treatment. The amount of pigment in the hair, its thickness, skin type, and the chosen settings also determine how well a hair responds.

After the anagen phase follows the relatively short catagen phase, in which active growth stops. After that, the follicle enters the telogen or resting phase. Eventually, the hair falls out and a new growth cycle can begin.

Over time, therefore, a new group of hairs becomes active. By repeating treatments at the appropriate intervals, new hairs can continuously be targeted at the moment they are most sensitive to the treatment.

The treatment interval is therefore not an arbitrary number of weeks between two appointments. It has to do with the biology of the area being treated.

How do IPL and laser work for hair removal?

The technology behind laser and IPL hair removal is based on selective photothermolysis.

That sounds more complicated than it is.

Melanin is the pigment that gives dark hair its color. This pigment can absorb light energy and convert it into heat. That heat is released in and around the hair follicle and can damage structures there that are necessary for new hair growth.

In doing so, you want to spare the surrounding skin tissue as much as possible.

That is where an important part of the treatment lies.More energy is not automatically better. The art is to get sufficient energy to the right place, attuned to the hair and the skin in which that hair grows.

Dark, strong hair contains a relatively high amount of melanin and therefore usually forms a good target. White and gray hairs contain hardly any melanin and are therefore difficult to treat effectively with light technology. Very light blonde and certain red hairs also respond less well.

Why does an armpit react differently than a leg?

We easily speak of body hair, while hair behaves quite differently biologically on different parts of the body.

I also see that during treatment processes.

Underarm hair is typically dark and coarse, and a relatively large number of hairs can be in the active growth phase at the same time. That is a favorable combination for a light treatment.

In the legs, the growth cycle proceeds differently, and treatment intervals are generally spaced further apart.

The face once again forms a separate category. Hair on the chin and jaw, in particular, can be strongly influenced by hormones. As a result, hair follicles that previously produced barely visible hair can become active over time.

That does not mean that facial hair is difficult to treat. Thick, dark hairs on the chin or upper lip, for example, can actually be very suitable for IPL or laser. It does mean, however, that the process may be different than for the armpits or legs.

Scientific research into long-term hair reduction also shows differences between body areas. Therefore, during a course of treatment, I look not only at the number of treatments someone has had, but especially at what the hairs are actually doing.

Are there fewer of them? Are they growing back more slowly? Are the remaining hairs becoming finer? Is the hair growth density changing?

That information tells me more than just the treatment number, and I use it to determine the next steps.

How many treatments do you need for laser or IPL hair removal?

That is probably the question I get most often.

A fixed number of treatments for everyone does not fit the way hair growth works. During the intake, I can make an initial assessment based on the skin, hair, and body area. Subsequently, the first treatments provide information on how the hair actually responds.

In that assessment, I look at, among other things:

• the body area
• the color and thickness of the hair
• the skin type
• the density of hair growth
• the growth cycle
• hormonal influences
• the technology and settings used
• the individual reaction of skin and hair

With dark, thick underarm hair, for example, a clear reduction can become visible relatively quickly. With hormonally influenced facial hair, the progression can be very different.

Therefore, during the process, I do not only look at how many hairs are left. The speed at which they grow back, their thickness, and their distribution across the treated area are also relevant.

As fewer hairs actively grow back, it may, for example, actually be beneficial to wait longer for the next group of hairs. The treatment interval can therefore change during a course of treatment.

I find that more sensible than setting the same number of treatments and the same standard schedule for everyone in advance.

Is laser hair removal permanent?

There is quite a bit of confusion surrounding the word permanent.

In scientific literature and regulations, therefore, there is often talk of permanent hair reduction or long-term hair reduction.

This does not mean that every hair follicle has disappeared forever and that no hair can ever appear again for the rest of your life. It concerns a long-term, stable reduction in the amount of hair that regrows after a course of treatment.

I find that difference important.

Hormones, age, and other changes in the body can also affect hair growth later on. This can play a particularly important role on the face.

In the meantime, a good treatment result can indeed make a big difference: significantly fewer hairs, a lower hair density, and remaining hairs that are finer and less noticeable. In daily life, this often means primarily that shaving is needed much less frequently and stubble is significantly reduced.

For some people, a maintenance treatment is desirable after a period of time.

That is why I prefer to speak about long-lasting hair reduction than about the promise that every single hair disappears forever. Not because the result is insignificant, but because it better describes what happens biologically.

What is better for hair removal: IPL or laser?

IPL and laser are often compared. However, the choice between IPL and laser in itself does not say much about the final result.

A laser produces light with a specific wavelength. For hair reduction, among other things, Alexandrite lasers around 755 nanometers, various diode lasers around 800 to 810 nanometers and the Nd:YAG laser with a wavelength of 1064 nanometers used.

That wavelength matters.

Melanin does not absorb light equally strongly at every wavelength. As a result, an Alexandrite laser has different properties than an Nd:YAG laser. The longer wavelength of Nd:YAG is absorbed relatively less strongly by melanin in the epidermis. That is one of the reasons why this technology holds an important place in the treatment of darker skin types.

IPL, Intense Pulsed Light, is technically not a laser.

An IPL system works with a broader spectrum of light. With the Lumenis M22, the part of the light spectrum suitable for the treatment is selected using various filters. For hair reduction, for example, filters of 640, 695, and 755 nanometers are available. These filters act as a lower limit: with the 755 nm filter, shorter wavelengths are blocked, and the spectrum starting from 755 nanometers is used.

This differs from, for example, an Alexandrite laser, which produces light around a single specific wavelength of 755 nanometers. IPL therefore remains broadband light, but that does not mean that the entire light spectrum is used unfiltered. It is precisely through the choice of filter that the spectrum used can be tailored to, among other things, the skin type and the characteristics of the hair.

Alexandrite, diode, Nd:YAG, and IPL are all used for long-lasting hair reduction. Research shows long-lasting hair reduction for various systems, with results depending on the system used and the body area, among other factors.

So the name of the device doesn't tell the whole story.

The quality of the system, the chosen spectrum or wavelength, the amount of energy, pulse duration, cooling, skin type, and hair characteristics all influence the treatment.

And then someone still has to put those variables together in the right way.

Why do the equipment and the practitioner matter?

A professional IPL or laser system offers various options to tailor a treatment. This also means that choices must be made.

At Medicademis, I work with the following for IPL hair reduction: Lumenis M22 system. Beforehand, I assess, among other things, the skin type, the amount of pigment in the skin, the color and thickness of the hair, and the body area.

During a course of treatment, I reassess the skin's response and the development of hair growth.

That is important. The settings someone starts with are not automatically the settings with which the entire process is completed.

Ultimately, a device is an instrument. The assessment of the skin and hair determines how I use that instrument.

Which hairs are not or less suitable for IPL or laser?

Pigment is needed for effective light treatment.

White and gray hairs contain too little melanin to absorb sufficient light energy. They are therefore not suitable for IPL or laser hair removal. Very light blonde and certain red hairs also respond significantly less well.

I am equally selective with very fine facial hair.

Not only because these hairs contain little pigment. During the treatment of fine hair growth on the face and neck, a rare reaction has also been described in which hair growth can actually increase. This is paradoxical hypertrichosis named.

This emphatically does not mean that facial hair in general cannot be treated. Dark, thick hairs on the chin, jaw, or upper lip may actually respond well.

It primarily means that you must first determine what is growing for her.

To someone standing in front of the mirror, it is all unwanted hair growth. For me, as a skin therapist, the difference between a thick terminal hair and fine vellus hair makes a difference in the decision to treat or not.

So sometimes a good review also means that I do not recommend IPL. For example, because the hair contains too little pigment or because I find another method more suitable.

Bumps and irritation after shaving: sometimes the question starts with the skin.

Not everyone comes to me because the hair itself is the biggest problem.

Sometimes it is precisely the consequences of shaving: red bumps, minor inflammations, itching, ingrown hairs, or dark spots left behind after an inflammation.

Then I first look at what is happening in the skin.

An ingrown hair can occur when a hair does not grow out properly through the skin surface or re-enters the skin after shaving. The skin may react to this with an inflammatory response.

For some people, it remains just a single red bump. For others, irritation recurs after almost every shave.

Ingrown hairs and pseudofolliculitis barbae

A skin problem closely associated with ingrown hairs is pseudofolliculitis barbae.

In this process, a hair penetrates the skin again after shaving, and an inflammatory reaction develops around that hair. It often occurs in the beard area, but the underlying mechanism of ingrown hairs can also cause problems on other shaved areas of the body.

Especially curly and thick hairs have a greater tendency to grow back towards the skin.

The inflammation can cause red or dark bumps.In skin prone to post-inflammatory hyperpigmentation, dark pigment spots may also remain after the inflammation.

If the hair repeatedly forms the trigger, it is logical to look not only at the inflammation but also at the hair itself.

By permanently reducing the number of hairs and making remaining hairs finer, the triggers for recurring ingrown hairs and inflammation can also decrease.

Laser hair removal is therefore also used as a treatment option for pseudofolliculitis barbae.

Folliculitis or ingrown hairs?

Not every bump around a hair follicle is an ingrown hair.

For example, there may also be a case of folliculitis, an inflammation of a hair follicle. That can look similar at first glance, but the cause does not necessarily have to be the same.

Acne and other skin conditions can also sometimes resemble inflamed hair follicles.

That distinction is relevant. IPL hair removal is not a general treatment for every red bump, every form of acne, or every skin inflammation.

If hair and shaving indeed play a significant role in the recurring nature of the symptoms, hair reduction, on the other hand, could be an interesting treatment strategy.

For me, that is the difference between just hair removal and looking at the skin first.

Why do dark spots appear after shaving?

I also see this regularly in combination with recurring irritation.

After an inflammation, the skin can temporarily produce extra pigment. This is called post-inflammatory hyperpigmentation. The inflammation will have already disappeared by then, while the dark spot can remain visible for weeks or much longer.

If every shave causes ingrown hairs and inflammation, a pattern of shaving, irritation, inflammation, and new pigment spots can develop.

In such a situation, I look not only at the pigment spot, but also at the cause of the recurring inflammation.

When hair plays a significant role in this, reducing hair growth can help break that cycle.

Why is it allowed to shave between IPL treatments but not wax?

Shaving is perfectly fine during a course of treatment.

With waxing, sugaring, or epilating, the hair is pulled out of the follicle. In doing so, you temporarily remove precisely the pigmented material that the light needs to target during a subsequent treatment.

When shaving, the hair remains present in the follicle. Only the portion that protrudes above the skin surface is cut off.

Therefore, shaving between treatments is the recommended method.

Laser and IPL hair removal and the sun: why is that important?

Here too, it revolves around melanin.

During the treatment, I want as much light energy as possible to be absorbed by the pigment in the hair and as little as possible by the surrounding skin.

Skin that has produced significantly more pigment due to the sun changes that ratio. The skin itself can then absorb more light energy.

Therefore, before a treatment, I ask about recent sun exposure and assess the current skin color. Depending on this, it may be necessary to postpone the treatment.

That is not a formality on an intake form. It is part of the safe application of lighting technology.

IPL hair removal at Medicadermis in The Hague

In my practice, I first assess whether IPL is suitable for the skin and hair growth. In doing so, I consider the skin type, hair color and thickness, hair growth density, and the body area. Recent sun exposure, medication, and hormonal factors can also be relevant.

For IPL hair reduction, I work with the Lumenis M22 system. The settings are tailored to the skin and hair and can be adjusted during the treatment process based on the reaction I observe.

You can find more information about the treatment per body area at IPL and laser hair removal of the face, IPL hair removal of arms and legs and IPL hair removal of the torso.

For hair that is not suitable for IPL due to its color or characteristics, can electric hair removal be an alternative.

If you are unsure which method suits your skin and hair growth, I can assess this during an initial appointment.

Frequently asked questions about IPL and laser hair removal

How many treatments do I need?

This varies by person and body area. Hair color, thickness, growth cycle, skin type, and hormonal factors all play a role. During the treatment process, I assess how hair growth changes, and the interval can be adjusted accordingly.

Is IPL the same as laser?

No. A laser works with a specific wavelength. IPL uses a broader spectrum of light, from which a specific portion is selected using filters. Both technologies can be used for long-lasting hair reduction.

Does IPL work on blonde hair?

The less pigment a hair contains, the more difficult it is to treat with light. Dark, strong hairs generally respond best. Very light blonde, white, and gray hairs are unsuitable or barely suitable.

May I shave between treatments?

Yes. Shaving is allowed. Waxing, sugaring, and epilating are discouraged because they remove the hair from the follicle.

Can IPL help with ingrown hairs?

When recurring ingrown hairs are caused by the hairs themselves and by shaving, long-term hair reduction can help reduce the cause. Laser hair removal is also used as a treatment option for pseudofolliculitis barbae.

Can IPL help with bumps after shaving?

That depends on the cause. Bumps can be caused by ingrown hairs or pseudofolliculitis, but also by folliculitis or another skin problem, for example. That is why I examine the skin first before determining whether IPL hair removal is a suitable treatment.

Can I get IPL hair removal if I am tanned?

Clearly tanned skin contains more melanin and can therefore absorb more light energy. This can be a reason to postpone a treatment. Therefore, before every treatment, I assess recent sun exposure and the current skin color.

Sources and further literature

For this article, use was made of scientific literature on selective photothermolysis, the hair growth cycle, long-lasting hair reduction with laser and IPL, pseudofolliculitis barbae, and paradoxical hypertrichosis. I combine the information from the literature with my professional assessment as a skin therapist. The suitability of a treatment remains dependent on the individual skin and hair growth.

About the author

Charlotte de Deugd is a skin therapist and owner of Medikadermis in The Hague.She works with non-invasive skin improvement and medical light and laser technology. In her articles, she writes about skin problems and treatments from the perspective of her profession as a skin therapist, and the considerations she makes in practice.