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The Hair Growth Cycle Explained: Stages, Timeline, and Hair Loss

In this article, we’ll explain the four stages of the hair growth cycle, how long each stage typically lasts, what can disrupt the cycle, and how treatments may support hair growth over time.

Close-up of a single human hair with a white bulb on the root, showing natural hair shedding and hair loss.

What Is the Hair Growth Cycle?

If you have been wondering, “What exactly is the hair growth cycle?” It is the repeated process each hair follicle goes through as it grows a hair, slows production, rests, and eventually sheds the old hair so another one can grow. Think of it like a schedule the hair follicles follow.

Every follicle on your scalp cycles independently, meaning it follows its own timeline. Your hairs are not all growing or shedding at the same time. If they were, you would lose all your scalp hair at once before it grew back, which is not how normal hair growth works.

So, if you have ever noticed some hairs on your pillow, in the shower, or on your brush, that can be normal. It just means some hairs have reached the shedding part of their hair cycle.

The hair growth cycle can also help explain why abnormal shedding and hair loss can happen. Stress, illness, aging, hormones, genetics, and pattern hair loss can all affect how follicles move through the cycle. When that cycle is disrupted, you may notice increased shedding, slower growth, changes in your hair density or thickness, or visible hair loss.

The 4 Stages of the Hair Growth Cycle

The hair growth cycle is divided into four main stages: anagen, catagen, telogen, and exogen.

Each stage plays a different role: anagen is when hair grows, catagen is when growth slows and the follicle transitions, telogen is when the follicle rests, and exogen is when the old hair sheds.

Anagen Phase: The Growth Phase

The growth stage of the hair growth cycle is called the anagen phase. This is when the follicle is actively producing hair, supported by a rich blood supply.

There are around 100,000 to 150,000 hair follicles on the scalp. In a healthy scalp, around 85 to 90% of scalp hairs are in the anagen phase at any given time. Because most scalp hairs are actively growing, overall density usually stays stable even while other hairs are resting or shedding.

All hairs on the body go through the anagen phase, but the duration of this phase varies depending on location. For scalp hair, the anagen phase usually lasts anywhere from two to six years, and sometimes longer, with hair growing at roughly 1 cm per month. This long growth phase is why scalp hair can grow much longer than most body hair. By comparison, thigh hair may stay in anagen for only a few months, while eyelashes have an even shorter growth phase of around 4 to 6 weeks.

How long your own hair can grow is mostly determined by genetics, although age, nutrition, hormones, overall health, and lifestyle can also play a role.

Catagen Phase: The Transitional Phase

The catagen phase is the short transition stage between active growth and rest. It is the shortest part of the hair growth cycle, lasting around two to three weeks. Only 1 to 3% of scalp hairs are in this phase at any given time.

During the catagen phase of hair growth, hair stops growing, the follicle begins to shrink, and the lower portion detaches from its blood supply. At this point, the hair becomes what is known as club hair.

Catagen helps shut down active growth and prepare the follicle for the resting phase. The hair does not usually fall out during this phase. Instead, it stays in place as the follicle moves toward the resting phase.

Telogen Phase: The Resting Phase

The resting stage of the hair growth cycle is called the telogen phase.

During the telogen phase of hair growth, the follicle is not producing hair. The old club hair remains in place, held loosely while the follicle stays inactive. Think of it like a hibernation phase.

Around 10 to 15% of scalp hairs are in telogen at any given time under normal conditions. This phase usually lasts two to four months, although the exact timing can vary.

Certain factors, including chronic stress, illness, poor sleep quality, nutritional deficiencies, and hormonal imbalances, may extend telogen or push more hairs into this stage.

Exogen Phase: The Shedding Phase

The exogen phase is often described as the shedding stage of the hair growth cycle. During exogen, newly developing hair continues to grow upward, pushing the club hair out, resulting in its ultimate shedding.

Losing around 50 to 100 hairs per day during exogen is normal. Shedding becomes more concerning when it is heavier than usual, lasts for an extended period, or happens alongside visible thinning or reduced density.

How Long Is the Hair Growth Cycle?

The time it takes to complete the hair growth cycle varies by person, follicle, and even the area of the scalp, but the general timeline is:

  • Anagen: around 2 to 6 years
  • Catagen: 2 to 3 weeks
  • Telogen: around 3 months
  • Exogen: overlaps with late telogen and early anagen

Knowing this timeline can help you set realistic expectations for how quickly you may see changes with hair loss treatments. Because each follicle is at a different point in the cycle, visible changes do not happen all at once.

Even when treatment is helping, follicles still need time to return to active growth, produce stronger hair shafts, and grow enough length for the change to be visible. This is one reason hair treatments often take 6 to 12 months to show noticeable results.

Because of this, judging your hair week by week can be misleading. A few days of extra shedding, one bad photo, or a flatter-looking hairstyle does not tell you much on its own. Hair changes slowly, and the cycle is not something you can accurately judge day by day with mirror checks.

How the Hair Growth Cycle Changes in Male Pattern Baldness

Male pattern baldness, or androgenetic alopecia, is a gradual change in how genetically sensitive follicles behave over repeated hair growth cycles.

In androgenetic alopecia, follicles in areas such as the hairline, temples, and crown are sensitive to dihydrotestosterone, or DHT. DHT is a hormone made from testosterone by the enzyme 5-alpha-reductase. In genetically susceptible follicles, DHT can bind to androgen receptors and gradually change how the follicle functions.

According to research, men with male pattern hair loss show elevated DHT production, higher 5-alpha-reductase activity, and increased androgen receptor activity in the areas of the scalp affected by balding. This helps explain why certain scalp areas tend to thin and bald, while other areas, such as the back and sides, are usually less affected.

The main cycle change caused by male pattern baldness is that the anagen phase becomes shorter. Because anagen is the active growth phase, affected hairs have less time to grow long, thick, and pigmented before the follicle moves toward rest and shedding.

Over repeated cycles, this shortening leads to follicle miniaturization. This means the follicle itself gradually shrinks and produces a smaller, weaker hair each time it cycles. A healthy scalp follicle usually produces a terminal hair, which is a thick, pigmented hair that is easy to see. As miniaturization progresses, the follicle may produce finer, lighter hairs that look more like vellus hairs, which are the very fine, soft, lightly pigmented hairs often described as “peach fuzz.”

In male pattern hair loss, anagen becomes shorter over time, while the telogen resting phase may stay the same or become longer. Eventually, the growth phase can become so short that new hairs barely appear above the scalp.

In other words, male pattern baldness may seem sudden, but the hair growth cycle has usually been changing for years before thinning becomes easy to see.

What Factors Can Affect the Hair Growth Cycle?

The hair growth cycle can be affected by genetics, DHT sensitivity, illness, stress, nutritional deficiencies, hormonal changes, medications, scalp inflammation, and autoimmune conditions. These factors can affect follicles in different ways: some gradually shorten the growth phase, while others trigger more sudden shedding.

Genetics and DHT sensitivity are the main drivers of male pattern baldness. In this case, the anagen phase becomes shorter over repeated cycles, leading to follicle miniaturization and finer hairs over time.

Other triggers, such as illness, major stress, surgery, crash dieting, rapid weight loss, certain medications, or nutritional deficiencies, can push more hairs than usual into the telogen phase. This can lead to telogen effluvium, a type of diffuse shedding that often appears a few months after the trigger.

Nutritional deficiencies, such as low iron or ferritin, low vitamin D, zinc deficiency, inadequate protein intake, or very low-calorie dieting, may disrupt normal cycling. Hormonal or medical issues, especially thyroid problems and major hormone changes, can affect hair growth or shedding patterns too.

Inflammation and autoimmune conditions can also interfere with normal growth. Scalp conditions such as seborrheic dermatitis or psoriasis may worsen irritation or shedding, while alopecia areata usually causes patchy hair loss.

How Hair Loss Treatments Work With the Hair Growth Cycle

Hair loss treatments take time because follicles move through growth cycles gradually. Even when a treatment is working, visible results usually appear only after follicles have re-entered growth and produced thicker, longer hairs.

The two FDA-approved non-surgical treatments for male pattern hair loss are minoxidil and finasteride, but they work in different ways.

Minoxidil mainly supports follicle activity. Research states that it supports regrowth by affecting the hair growth cycle, including shortening the telogen (resting) phase, encouraging resting follicles to enter anagen sooner, and increasing follicle size over time. Its exact mechanism is not fully understood.

Finasteride, on the other hand, slows the process behind male pattern hair loss. It reduces DHT, helping lower the hormonal pressure that shortens the growth phase in susceptible follicles. In doing this, finasteride can help protect existing hair and slow further thinning.

For some men, one treatment may be enough. For others, combining both may be more effective because they target different parts of the problem: finasteride helps slow miniaturization, while minoxidil helps encourage growth from follicles that are still active.

The right choice depends on your hair loss pattern, how far the thinning has progressed, your medical history, and whether you are comfortable with long-term treatment. Neither option is a quick fix, and both need consistent use before results can be judged properly.

Can You Tell What Stage of the Hair Growth Cycle You Are In?

Not by looking in the mirror. You cannot tell whether individual follicles are in anagen, catagen, telogen, or exogen just by checking your scalp. What you may notice are signs that your hair cycle is changing, such as heavier shedding, finer regrowth, changes in texture, or more scalp showing in certain areas.

These signs can tell you that something may be changing, but they cannot show exactly which phase each follicle is in.

For example, some men using minoxidil for the first time experience a 3- to 6-week period of increased shedding. This is sometimes called the dread shed, and it can be a sign that older hairs are being pushed out as the follicles enter the active growth phase.

So while shedding, texture, and density changes can provide clues, they are not enough to identify the exact stage of the hair growth cycle.

Why the Hair Growth Cycle Makes Progress Hard to Judge

The hair growth cycle makes progress difficult to judge because hair changes slowly, follicles are not synchronized, and visible improvement usually appears gradually.

At any given time, some follicles may be growing, some may be resting, and others may be shedding. A treatment may be helping follicles move toward a healthier cycle, but the visible difference can still take months to show.

This is why day-to-day checks can be misleading. Lighting, styling, hair length, wetness, camera angle, and scalp exposure can all change how your hair looks. One bad photo does not prove your hair loss is getting worse, and one better-looking day does not prove regrowth.

For men using treatment, the more reliable approach is to compare progress across consistent time intervals. Monthly photos, side-by-side comparisons, and structured scalp scans can help you track your hair loss progress more accurately.

FAQs

What are the 3 stages of hair growth?

The three main stages of hair growth are anagen, catagen, and telogen. Anagen is the growth phase, catagen is the transition phase, and telogen is the resting phase. Exogen is often discussed separately as the shedding stage.

What is the growth stage of the hair growth cycle called?

The growth stage of the hair growth cycle is called the anagen phase. This is when the follicle actively produces hair.

What is the resting stage of the hair growth cycle called?

The resting stage of the hair growth cycle is called the telogen phase. During telogen, the follicle rests and the old hair remains in place before shedding.

What is the shortest part of the hair growth cycle?

The shortest part of the hair growth cycle is the catagen phase. It usually lasts only a few weeks.

Does hair grow in cycles?

Yes. Hair grows in cycles. Each follicle moves through growth, transition, rest, and shedding before beginning the process again.

How can you increase the anagen phase of hair naturally?

You can support a healthy hair growth cycle by correcting nutritional deficiencies, managing underlying health triggers, treating scalp inflammation, getting enough sleep, and maintaining overall health. However, for male pattern baldness, natural methods alone usually are not enough to reverse DHT-driven follicle miniaturization. Evidence-based treatments like minoxidil and finasteride are typically more relevant.

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