The Hair Growth Cycle: 4 Stages Explained

If you’ve spent any time on hair or dermatology TikTok, you might’ve heard about the hair growth cycle. And so you might be wondering, what is the hair growth cycle, exactly? 

Human hair goes through four distinct stages as it grows to full length, rests, and eventually sheds. This happens over the course of several years, all before starting the cycle again.

Whether you’re concerned about hair loss or just curious about how your hair grows, we’ve got you. Below, we’ve explained the phases of the hair growth cycle in detail. 

Your hair goes through four growth phases:  

• The anagen phase. This is the active growing phase, during which your hair grows to its full length.

• The catagen phase. This phase marks a transition of the hair from active growth into a resting phase.

• The telogen phase. During this phase, your hair follicle becomes dormant and the hair strand doesn’t actively grow.

• The exogen phase. Here, the hair strand sheds from the follicle.

Once a strand of hair sheds from the follicle, the hair growth cycle starts again, with a new hair growing from the same follicle. If you’re wondering whether it’s breakage or new growth atop your head, you can learn more about what new hair growth looks like.

Every hair follicle is on its own schedule. While one follicle might be in the anagen phase, the one right next to it might be in the telogen phase. (Think about it: if all your hair follicles entered the exogen stage at the same time, you’ll lose all your hair at once!)

Below, we’ve explained each hair growth phase in more detail to help you better understand the hair growth process.

The Anagen Stage

During the anagen phase, your hair actively and continuously grows. About 85 to 90 percent of your hairs are in this stage at any given time.

While all of the hair on your body goes through the anagen phase, the duration of this phase varies depending on the location. One thing you might be wondering is how long the hair growth cycle time is from beginning to end. On average, your scalp hair grows for between two and six years before reaching the end of the anagen phase. In comparison, the anagen phase for thigh hair is around two months.

This time variation in the anagen phase is the reason why the hair on your scalp generally grows much longer than the hair on your face and body.

The Catagen Stage

After passing through the anagen phase, each hair follicle enters the catagen phase. Also referred to as the regression or transition phase, this period of the growth cycle involves the formation of a club hair — a hair shaft that’s detached from the blood supply of the follicle.

During the catagen phase, your hair stops actively growing and the hair follicle, which previously supplied the hair with nutrients, shrinks slightly. This phase lasts for several weeks.

The Telogen Stage

During the telogen phase, the hair follicle rests. The hair shaft also remains in a resting state, with no ongoing growth.

Between 10 and 15 percent of the hairs on your scalp, face, and body are in this phase at any given time.

Like the anagen phase, the telogen phase varies in length. Most body hair has a short telogen phase that only lasts for a few weeks, while scalp hair can go through a telogen phase of up to one year.

The Exogen Stage

As new hair starts to grow from the hair follicle, the old hair enters into the exogen phase, or shedding phase.

During this final phase, the hair fiber detaches from your scalp and falls out. It’s normal to shed about 50 to 100 hairs every day through this process.

You may notice these hairs on your pillowcase, in your hairbrush, or stuck inside your shower drain. Don’t panic — this is normal, everyday hair shedding — not hair loss. 

Since each hair is replaced by a new one growing from the same follicle, the hair shedding that occurs in the exogen phase doesn’t lead to hair loss. 

Your hair is made up of two separate structures, both of which play a role in growth.

The first structure is the hair follicle, which lies under the surface of your scalp. Your hair follicles are living structures that produce new hairs through a complex process involving the creation of new cells.

The second structure is the hair shaft. This is the part of your hair that grows out from your epidermis and includes most of the visible follicular structure.  

Each hair shaft grows from the hair bulb — an area of the hair follicle that converts nutrients into the keratinized cells that make up your hair.  

Your hair grows about one inch every two months. 

This translates to about three inches of hair growth in a six-month period and six inches of hair growth over the course of one year. A lifetime of hair growth would represent about 30 cycles.

But a number of issues can interrupt the hair growth cycle, which can sometimes slow down the growth rate. 

Just like other processes in your body, the hair growth process can be interrupted and affected by factors like stress, malnutrition, and illness.

Certain health issues, such as stress, infections, or illnesses that cause fever, may cause many hair follicles to prematurely enter the telogen phase of its growth cycle, resulting in a form of hair loss that’s referred to as telogen effluvium.

Telogen effluvium can be triggered by:

• Severe acute stress

• Infections and illnesses

• Nutritional deficiencies 

• Hormonal changes

Again, the telogen phase is a resting phase. Telogen effluvium makes your hair enter the telogen phase prematurely, where it might stay for a few months before shedding. For this reason, if you have telogen effluvium, you might only notice excessive hair fall a few months after you experience the trigger. 

The good news? Telogen effluvium is temporary — your hair growth cycle will usually recover after you deal with the underlying issue. 

Other, potentially permanent types of hair loss include androgenetic alopecia (male pattern baldness), alopecia areata (an autoimmune condition), and injuries to the head, scalp, or follicles.

Male Pattern Baldness and the Hair Growth Process

Male pattern baldness is the most common form of hair loss in men. Unlike telogen effluvium, which is temporary, hair loss due to male pattern baldness is permanent.

This form of hair loss is caused by a combination of your genetic makeup and the effects of dihydrotestosterone (DHT), an androgen (a male hormone). 

Over time, DHT can bind to receptors in your scalp and cause your hair follicles to go through a process called miniaturization. During this process, your hair follicles shrink and eventually stop producing new hairs.

Some research suggests that DHT stimulates TGF-β1, TGF-β2, DKK1, and interleukin 6, which are proteins that play a role in your hair growth cycle.

Not all of your hair follicles are sensitive to DHT. Most of the time, male pattern baldness affects the follicles around your hairline and crown, without any effect on the hair at the back and sides of your scalp.

Hair care is about more than shampooing and getting trims every so often. In fact, hair health is determined in large part by how you care for it.

Simple habits can help you to promote healthy hair growth and avoid some causes of hair loss. 

We’d recommend:

• Eating a balanced, nutrient-rich diet. A healthy diet supports the hair growth cycle by ensuring your hair follicles have enough nutrients to produce hair cells. 

• Use a supplement if necessary. If you have a nutritional deficiency, a healthcare professional might suggest a supplement. Certain supplements, like our biotin gummies, contain important vitamins for hair growth.

• Take care of your scalp. Certain scalp conditions can affect the hair growth cycle. Practice scalp care by addressing issues like dandruff when they come up.

• Quit smoking. You already know that smoking can have a terrible effect on your health — but did you know that smoking may worsen hair loss? Consider trying a smoking cessation program.  

Read more about the best foods for hair health and check out our ultimate list of hair care tips for men.

Since hair loss can occur for several reasons, there’s no one-size-fits-all method for regrowing hair. The most effective way to regrow your hair will depend on how you lost it.

As mentioned, if you have telogen effluvium, addressing the underlying cause — whether it’s acute stress or a nutritional deficiency — is the first step in promoting hair regrowth.  

But if you’re experiencing other forms of hair loss, like male pattern baldness, your best bet is to treat it with medication.  

Medication for Hair Growth

There are two FDA-approved medications currently available to treat male pattern baldness: 

• Finasteride, a prescription-only oral medication that prevents your body from producing DHT, the hormone that contributes to male pattern hair loss

• Minoxidil,  a topical, over-the-counter medication that works for a number of types of hair loss by encouraging your hairs to enter into the anagen stage of the hair growth cycle

We offer oral finasteride, minoxidil foam, and minoxidil solution online. You can also get the best of both worlds by trying our topical finasteride and minoxidil spray.

Word to the wise: It’s important to understand that you can only regrow hair in the areas of your scalp with healthy, active hair follicles. If you’ve lost hair in a specific part of your scalp for several years, such as a receding hairline, it may not grow back, even with daily finasteride and minoxidil use.

There’s also no guarantee that the hair you’ve lost due to male pattern baldness will grow back, even in areas where it’s only recently started to thin. (At that point, your best possible course of action may be a hair transplant.)

That’s why it’s important to treat hair loss ASAP: As soon as you notice the early signs of balding, make an appointment with a healthcare professional to talk about hair loss treatments. 

Each hair follicle cycles through the stages of the hair growth process over the course of your life. Sometimes, though, this hair growth cycle is interrupted.

Here’s what to keep in mind: 

• There are four stages of hair growth: Anagen, catagen, telogen, and exogen (shedding). Once your hair strand sheds, a new hair should start growing from the same hair follicle. 

• Sometimes, this cycle is interrupted. Issues like acute stress or severe illness can cause your hair follicles to shift into telogen (resting) phase early, which can lead to sudden hair shedding. 

• There are many treatments for hair loss. Minoxidil and finasteride, for example, are two science-backed hair loss treatments. 

If you’ve noticed the signs of hair thinning and want to take action, you can view our full range of proven, science-based hair loss treatments online.

You can also find out more about the common signs of hair loss, risk factors and treatments in our detailed guide to male pattern baldness.