Every hair on your head follows the same repeating pattern, called the hair growth cycle. It moves through four distinct stages: anagen (active growth), catagen (transition), telogen (rest), and exogen (shedding). Each hair follicle runs through this life cycle on its own schedule. This is why you grow new hair and shed old hair at the same time without going bald overnight.
Understanding the four stages of hair growth helps you tell normal from excessive shedding apart. It explains why treatments that support the cycle can help. Here is how each phase works, what can disrupt it, and what you can do about it.
The hair growth cycle at a glance
- Anagen (growing phase): about 2 to 7 years. Roughly 85 to 90% of scalp hair. Hair actively grows from the follicle.
- Catagen (transition phase): about 2 to 3 weeks. Around 1 to 3% of hair. Growth stops, and the follicle shrinks.
- Telogen (resting phase): about 3 months. Roughly 10 to 15% of hair. The hair rests while a new hair forms below it.
- Exogen (shedding phase): ongoing. The old hair is shed. Losing 50 to 100 hairs a day is normal.
The Four Stages of Hair Growth
| Phase | What happens | Typical duration | Share of scalp hair |
|---|---|---|---|
| Anagen (growth) | Hair actively grows from the follicle | 2 to 7 years | 85 to 90% |
| Catagen (transition) | Growth stops; the follicle shrinks | 2 to 3 weeks | 1 to 3% |
| Telogen (rest) | Hair rests; a new hair forms beneath it | About 3 months | 10 to 15% |
| Exogen (shedding) | The old hair is shed; a new one replaces it | Ongoing | Varies |
1. Anagen Phase: The Active Growth Stage
The anagen phase is the active growth stage and the longest part of the cycle, lasting about two to seven years for scalp hair. During this time, fed by a rich blood supply at the root, cells in the hair bulb divide quickly and push the growing hair shaft up and out of the follicle. Roughly 85 to 90 percent of your hair is growing at once, which is why a healthy scalp looks full.
Scalp hair grows about half an inch (1.25 cm) per month on average, though your growth rate varies with genetics, age, and hormones. How long anagen runs also depends on the type of hair: scalp hair keeps growing for years, while body hair, eyebrows, and lashes finish much sooner, which is why they never grow as long. The length of this stage is largely inherited, and it sets how long your hair can ultimately get.
2. Catagen Phase: The Transition Stage
Catagen is a short transition phase that lasts about two to three weeks and affects only 1 to 3 percent of your hair at any time. When a hair enters catagen, growth stops. The lower part of the follicle shrinks, and the hair detaches from the dermal papilla, the structure that supplies nutrients and blood at the base of the root.
Cut off from its supply, the strand becomes a club hair: a fully formed hair held loosely in place. Hairs during the catagen phase are no longer growing but have not yet been shed. The stage is brief but necessary, closing out active growth and preparing the follicle to rest.
3. Telogen Phase: The Resting Stage
In the telogen phase, the follicle rests. This resting stage lasts about three months, and around 10 to 15 percent of your scalp hair is in it at any given time. The club hair sits in place and does not grow, while a new hair begins to form in the follicle beneath it. Nothing looks dramatic on the surface, but the groundwork for the next cycle is being laid.
Certain triggers can push an unusually large share of hair to enter the telogen phase early, a pattern known as telogen effluvium, which leads to heavier shedding a few months later. If shedding increases or the resting phase seems to run long, a specialist can help identify the cause.
4. Exogen Phase: The Shedding Stag
The exogen phase is the shedding phase, and it overlaps with telogen. This is when the old hair is finally released and falls away, often while you wash or brush. Shedding 50 to 100 hairs a day is completely normal, and each one is usually being replaced by a new hair growing up from the same follicle.
Once that strand is shed, the follicle re-enters anagen and starts the cycle again. Losing some hair every day is not a sign of a problem. Sudden, heavy, or patchy shedding that goes well beyond the normal range is the signal worth attention.
Why You Do Not Lose All Your Hair at Once
Each follicle runs through the hair growth cycle independently, on its own timeline. Your scalp holds roughly 100,000 follicles, and they do not move through the phases together. While the large majority are in active growth, others are transitioning, resting, or shedding at the same time. This mosaic of different hair cycles is the reason healthy shedding looks like a few dozen strands a day rather than clumps. Thinning becomes visible when these follicle cycles fall out of sync: either too many hairs shift into the resting phase at once, or follicles start producing progressively thinner hair with each pass through the cycle.
Factors That Affect Your Hair Growth Rate and Cycle
Several factors affecting hair growth rate and the length of each phase are outside your control, and several are not. These are the ones that matter most.
Genetics and Age
Genetics set the baseline for your hair growth patterns: how long your anagen phase runs, how fast your hair grows, and how dense it is. Age matters too. As you get older, the anagen phase tends to shorten, and follicles produce finer strands, so hair growth slows, and overall density can decrease. These shifts are normal, though their pace varies from person to person.
Hormonal Changes
Hormones strongly influence hair follicle function. Levels shift during pregnancy, after childbirth, and through menopause, and each can change the balance of the hair growth cycle. Thyroid disorders are another common driver: conditions like Hashimoto’s disease can contribute to hair thinning by disrupting the cycle. Learn more about the link between Hashimoto’s disease and hair loss.
The hormone most associated with pattern hair loss is dihydrotestosterone (DHT). In people who are genetically sensitive to it, DHT gradually shrinks follicles over successive cycles. If you notice unexplained changes in your hair alongside other symptoms, it is worth checking your hormone health with a doctor
Nutrition
Hair is built mainly from protein, and follicles need a steady supply of nutrients to keep producing healthy strands. When intake falls short, follicles can weaken or stall in the resting phase. Diets low in protein, iron, zinc, vitamin D, or biotin are linked with more shedding and slower regrowth. A balanced diet that covers these bases gives the cycle what it needs. Correcting a genuine deficiency can help, but taking large amounts of supplements you do not need generally will not speed things up.
Scalp Health
The scalp is the foundation for healthy hair growth. Dandruff, excess oil, and inflammation can interfere with the follicles and the local blood supply. Keeping the scalp clean and treating conditions such as seborrheic dermatitis or psoriasis supports a healthier environment for hair to grow. Gentle scalp massage may also help stimulate blood flow to the follicles.
Stress and Illness
A physical shock, a high fever, surgery, childbirth, or a stretch of severe stress can push a large number of hairs into the resting phase at once. Two to three months later, those hairs shed together in a wave, the pattern called telogen effluvium. It usually reverses on its own once the trigger passes and the hairs re-enter the growth phase, though full recovery can take several months.
How Hair Loss Disrupts the Growth Cycle
Most hair loss traces back to a disruption somewhere in the cycle, whether hairs shed too early, rest too long, or the follicles themselves shrink. In androgenetic alopecia, the most common form of hair loss, DHT sensitivity causes follicles to miniaturize over time.
With each cycle, affected follicles shrink, the anagen phase shortens, and the hair they produce becomes finer and lighter, shifting from thick terminal hair to wispy vellus hair. Eventually, some follicles stop producing visible hair altogether. Because the change is gradual, early treatment tends to work better than waiting.
Common Hair Loss Conditions
Disruptions to the cycle often show up as one of these conditions:
- Androgenetic alopecia (male or female pattern hair loss): the genetic, DHT-driven miniaturization described above, and the most common cause of hair loss or thinning.
- Telogen effluvium: a temporary surge of shedding when many hairs enter the telogen phase early, usually after stress, illness, or hormonal change
- Alopecia areata: an autoimmune condition in which the immune system attacks healthy follicles, causing patchy hair loss.
Each of these disrupts the normal balance between the anagen, catagen, and telogen phases. Many are manageable, and several respond well to treatment, especially when addressed early.
How to Support a Healthy Hair Growth Cycle
Everyday Hair and Scalp Care
Small, consistent habits matter more than any single product for maintaining hair health:
- Wash regularly to keep oil and buildup from clogging follicles.
- Use gentle, sulfate-free shampoos that do not strip natural oils.
- Add occasional scalp massage to encourage blood flow.
- Avoid tight hairstyles and frequent high heat, which stress the hair shaft and cause breakage.
- Eat a balanced, protein-rich diet and stay hydrated.
None of this rewrites your genetics, but it gives every stage of the cycle a better environment to work in.
Treatment Options for Regrowth
When loss is progressive, several options can help prevent or treat premature hair loss by supporting the cycle:
- Minoxidil: a topical treatment that is FDA-approved for hair loss and works in part by prolonging the anagen phase.
- Finasteride: an oral, FDA-approved medication for male pattern hair loss that lowers DHT.
- Other options: low-level laser therapy, nutritional support, and, for the right candidate, procedures such as hair transplantation. Surgical options are reviewed during a consultation to see whether they suit your situation.
For people who want a more personalized plan, HairClub RX is a DNA-informed hair loss treatment program available at participating locations. It begins with a simple cheek-swab DNA test, reviewed with a licensed telehealth provider, to help match ingredients to your biology rather than relying on a one-size-fits-all product.
When appropriate, a provider may prescribe a custom-compounded medication that can combine active ingredients such as minoxidil and finasteride, paired with in-center hair therapy and progress tracking over time. For the right candidate, a personalized approach like this may help support healthier hair growth, improve density, and reduce shedding.
Individual ingredients such as minoxidil and finasteride may be FDA-approved on their own, but a compounded combination is not FDA-approved, and results vary. A HairClub specialist can review whether it is a fit during a free consultation.
