Hair Growth Phases and How They Affect Laser Hair Removal

For hair to fully renew, it goes through several successive stages of development. The hair growth phases explain why hair constantly sheds and regrows, as well as why laser hair removal cannot remove all unwanted hair in a single session. In this article, we will explain how the hair growth cycle works, what anagen, catagen, telogen and exogen are, and how hair growth differs on the scalp and on the body. We will also look at why understanding these processes is important for anyone considering a course of laser hair removal.

Please note! The information in this article is provided for educational purposes only and does not replace medical advice. If you notice excessive hair loss, a sudden change in hair structure or any other unusual symptoms, we recommend consulting a dermatologist or trichologist to determine the cause and receive individual recommendations.

What Is the Hair Growth Cycle?

Many people think of hair growth as a continuous process: a hair appears, gradually becomes longer and then simply falls out. In reality, the process is much more complex. Each hair goes through its own growth cycle, consisting of several successive phases. During each phase, different biological processes take place within the hair follicle, determining hair growth, nourishment, shedding and the formation of new hair.

It is important to understand that not all hairs are at the same stage of development at the same time. While one hair is actively growing, another may already be entering the resting phase, while a third is about to fall out. This is why hair is renewed gradually rather than all at once.

This mechanism applies to hair growth both on the scalp and on other parts of the body. However, the duration of individual phases can vary significantly depending on the area. This is why scalp hair can grow to a considerable length, whereas hair on the arms, legs or other parts of the body usually remains much shorter.

Understanding how the hair growth phases work is important not only for maintaining healthy hair. This knowledge also helps explain how various hair removal methods work. In particular, the hair growth cycle is one of the main reasons why the results after the first laser hair removal session may not be sufficient.

How Does Hair Grow?

To understand how the hair growth phases work, it is first worth briefly looking at where hair is formed and what determines its growth. Most people think of hair as the part visible above the skin’s surface. In reality, this is only the hair shaft, which is made primarily of keratin and no longer participates in biological processes. The most important changes take place much deeper — inside the hair follicle.

The follicle contains cells that continuously divide and form new hair. It also contains the dermal papilla, which supplies oxygen and nutrients necessary for hair growth. As long as the follicle remains active, the hair continues to grow. When its activity gradually decreases, the hair growth cycle moves on to the next stage.

It is important to understand that each follicle functions independently of the others. This is precisely why the hairs in one area of the body are not all in the same phase of development. Some are just beginning to grow, others are completing their life cycle, and still others are preparing to shed.

This is also what explains how laser hair removal works. A laser can effectively target hair only when it is in a particular phase of development. To understand why, let’s take a closer look at each stage of the hair growth cycle.

Anagen – the Active Growth Phase

Anagen is the first and most important phase of the hair growth cycle. This is when the hair actively forms and grows. During anagen, the hair is most firmly connected to the follicle. It receives nourishment, contains the highest amount of melanin and continues to grow. The duration of this phase depends on the area of the body. For example, scalp hair growth can remain in anagen for 2 to 7 years, and sometimes even longer. Body hair growth has a significantly shorter anagen phase — usually from several months to around a year. This is why hair on the legs, arms and other areas does not reach the same length.

Anagen is also the phase when hair is most susceptible to the effects of a laser. During laser hair removal, light energy is absorbed by melanin — the natural pigment found in hair. It is then converted into heat, which in turn affects the structures of the follicle responsible for further hair growth.

The more melanin the hair contains and the more strongly it is connected to the follicle, the more effectively thermal energy is transferred. This is why anagen is considered the optimal phase for laser hair removal.

However, there is one important consideration. At any given time, only some of the hair is in anagen. The rest has already moved into later phases or has not yet returned to active growth. This is why a single session can effectively target only part of the hair, while other hairs will become accessible to the laser only after a certain period.

Catagen – the Transition Phase

After anagen ends, the hair enters the next stage — catagen. This is the shortest phase of the hair growth cycle, usually lasting only 2–3 weeks. During this period, active growth virtually stops, and the hair follicle gradually begins transitioning into a resting state.

During catagen, the cells stop dividing actively, and the lower part of the follicle contracts. The dermal papilla gradually separates from the hair, meaning that the hair no longer receives full nourishment. However, the hair itself remains inside the skin, even though it is no longer growing.

Because the connection with the dermal papilla is lost, laser hair removal is less effective during this stage. During anagen, thermal energy can be readily transferred to the cells responsible for hair growth, whereas during catagen this connection has already been significantly disrupted. As a result, it becomes much more difficult for the laser to affect the structures responsible for the formation of new hair. Fortunately, catagen is a very short phase. At any given time, only a small proportion of hair is in this stage.

Telogen – the Resting Phase

After catagen ends, the hair enters telogen — the resting phase. During this period, the hair no longer grows, and the hair follicle temporarily stops its active work. However, this does not mean that the hair falls out immediately.

During telogen, the hair remains inside the follicle, although it no longer receives nourishment. It is held in the skin only mechanically and gradually prepares to shed. At the same time, the follicle begins to recover in preparation for starting a new hair growth cycle. This is why people sometimes mistakenly believe that hair continues to grow during this phase. In reality, if you look closely, its length is no longer increasing.

From the perspective of laser hair removal, telogen is also not a favourable phase. Since the hair has already lost its active connection with the dermal papilla, thermal energy can no longer effectively reach the cells responsible for further growth. This is why laser treatment is significantly less effective on hair in telogen than during anagen. The duration of this stage depends on the area of the body. For scalp hair, telogen can last for several months, whereas for body hair this period is generally shorter.

Exogen – the Hair Shedding Phase

The final stage of the hair growth cycle is exogen. During this phase, the hair finally leaves the hair follicle. Although many sources group exogen together with telogen, modern trichology increasingly considers it a separate phase because this is when the actual shedding of the hair takes place.

During exogen, the old hair is no longer held within the follicle and gradually falls out. This can happen while washing the hair, brushing, shaving or even without any mechanical action. At the same time, a new hair is already beginning to form inside the same follicle. It will soon enter anagen and begin a new hair growth cycle.

Therefore, shedding a certain amount of hair every day is a completely natural process. For healthy hair, this is not a sign of a problem but part of the continuous renewal cycle. The body constantly replaces old hairs with new ones, maintaining the density of the hair covering.

From the perspective of laser hair removal, exogen is of little practical significance. The hair has already completed its life cycle and will soon fall out, so there is little point in targeting it. For an effective treatment, it is much more important to wait until the new hair enters anagen.

Now that we have looked at all four phases of hair development, a logical question arises: how much hair is in each phase at any given time?

How Much Hair Is in Each Phase?

Although all hairs go through the same stages of development, they do not do so at the same time. At any given moment, some hairs are actively growing, some are in the resting phase, and others are preparing to shed. This is why hair is renewed gradually, rather than the entire hair covering being lost at once.

The proportion of hair in each phase depends on the area of the body, age, hormonal background and individual characteristics. For most healthy people, the distribution looks approximately as follows.

These figures are most representative of scalp hair, where the anagen phase lasts the longest. For body hair growth, the proportions may differ because the active growth phase is significantly shorter.

The most important point is that approximately 10–20% of scalp hair is not in anagen at any given time. This means that even the most advanced laser hair removal technology cannot affect all hair equally effectively during a single session.

Why Does Laser Hair Removal Work Only During Anagen?

After looking at all the hair growth phases, it becomes clear why a course of laser hair removal consists of several sessions. However, one important question remains: why does the laser work best specifically during anagen?

During the procedure, the laser’s task is not to remove the visible part of the hair, but to target the structures responsible for its further growth.

This is most effective during anagen because, at this stage:

• the hair is firmly connected to the hair follicle;
• cells are actively dividing and supporting hair growth;
• the hair contains the highest amount of melanin;
• thermal energy can readily reach the structures responsible for further hair growth.

The situation changes during the later phases.

For this reason, laser hair removal sessions are performed at specific intervals. During this time, new hairs naturally enter anagen and become susceptible to the laser’s effects. After each subsequent session, the number of actively growing hairs gradually decreases, and the results become increasingly noticeable. It is important to understand that this is not a limitation of the technology. It is a natural feature of the hair growth cycle that cannot be changed.

At LaserVille centres, a course typically consists of 8 sessions. This number of treatments allows the laser to target hairs as they gradually enter the anagen phase and helps achieve the best possible long-term results.

Can You Speed Up the Hair Growth Cycle?

After starting a course of laser hair removal, many people want to see results as quickly as possible. This is why a common question is: can you speed up the hair growth cycle to get more hairs into the anagen phase sooner?

At present, there are no scientifically proven methods that would allow you to safely and significantly alter the natural progression of the hair growth phases. The duration of each phase is largely determined by genetics and depends on many factors, including age, hormonal balance, overall health and individual characteristics.

At the same time, healthy hair is influenced to some extent by:

• a balanced diet;
• sufficient protein, iron, zinc and other micronutrients;
• avoiding vitamin deficiencies;
• a normal hormonal balance;
• proper care of the skin and hair.

All of these factors help support the normal functioning of the hair follicles, but they cannot intentionally move hair from telogen or catagen into anagen.

That is why, during a laser hair removal course, the best approach is to follow the recommended intervals between treatments. During this time, hair naturally enters the active growth phase, allowing the laser to target it as effectively as possible during the next session. Having a treatment too early will not speed up the results, because a significant proportion of the hair may not yet have entered anagen.

Common Myths About Hair Growth Phases

There are many myths surrounding the hair growth cycle. Some are so widespread that people often accept them as established facts. Let’s look at some of the most common ones.

Myth 1. Shaving Makes Hair Enter Anagen Faster

Shaving only cuts the part of the hair that is above the skin’s surface. It does not affect the hair follicle or change the hair growth phases. Therefore, after shaving, anagen, catagen, telogen and exogen continue as normal.

Myth 2. All Hair Grows at the Same Time

In reality, each hair follows its own hair growth cycle independently of the others. This is why hair is gradually renewed rather than all being shed at the same time.

Myth 3. If a Hair Falls Out, the Follicle Stops Working

Hair shedding does not mean that the follicle has stopped functioning. In most cases, after the old hair completes the exogen phase and falls out, the follicle remains active and begins a new cycle of growth.

Myth 4. One Laser Hair Removal Session Is Enough

Even the best lasers for hair removal cannot effectively target hair that is outside the anagen phase. This is why a course of treatments is necessary to achieve long-lasting results, gradually targeting hairs as they enter the active growth phase.

Conclusion

The hair growth phases are a natural biological process that affects not only the condition of healthy hair but also the effectiveness of modern hair removal methods. The hair growth cycle explains why hair is renewed gradually and why laser hair removal cannot achieve maximum results after a single treatment.

Understanding how anagen, catagen, telogen and exogen work helps you assess the results of a laser hair removal course realistically and avoid expecting an immediate effect. Following the recommended intervals between treatments makes it possible to target hair when it is most responsive to laser energy.

If you would like to find out how many treatments you may need in your individual case, contact the specialists at LaserVille for a free consultation. Before starting a course, our specialists will assess your hair growth characteristics, answer your questions and help you choose the most suitable treatment plan.