Understanding the Hair Growth Cycle: An Overview
Hair Loss Science
Understanding the Hair Growth Cycle: An Overview
Every hair on your head runs on its own clock, cycling through growth, transition, rest, and shedding. The four phases explain how hair loss happens and how treatments work.
Key takeaways
- The cycle has four phases: anagen (growth), catagen (transition), telogen (rest), and exogen (shedding).
- About 85 to 90% of scalp hairs are growing at any time. Anagen lasts 2 to 7 years and sets your maximum hair length.
- Losing 50 to 100 hairs a day is normal. Genetics, hormones like DHT, age, and nutrition can shorten growth and increase shedding.
- After a transplant, new hairs often shed during a temporary resting phase. New growth typically begins within a few months.
Hair growth is a fascinating and complex process with multiple phases. Understanding the hair growth cycle is essential to understanding how hair loss occurs and how hair restoration treatments work. Here is each phase, and why it matters.
The four phases of the hair growth cycle
| Phase | Duration | Share of scalp hair | What happens |
|---|---|---|---|
| Anagen (growth) | 2 to 7 years | About 85 to 90% | Hair cells divide rapidly and the hair shaft lengthens |
| Catagen (transition) | 2 to 3 weeks | About 1 to 2% | The follicle shrinks and the hair detaches from its blood supply |
| Telogen (resting) | 2 to 4 months | About 10 to 15% | Growth stops; the hair rests in the follicle |
| Exogen (shedding) | Overlaps with telogen | 50 to 100 hairs shed a day | The old hair sheds and a new anagen hair begins |
1. Anagen phase (growth phase)
Duration: 2 to 7 years. The active growth phase of the follicle. Hair cells divide rapidly and the hair shaft lengthens. The length of the anagen phase determines the maximum length your hair can grow. Approximately 85 to 90% of the hairs on your scalp are in this phase at any given time.
2. Catagen phase (transition phase)
Duration: 2 to 3 weeks. A short transitional phase that marks the end of active growth. The follicle shrinks and the hair detaches from its blood supply, moving into a resting state. Only about 1 to 2% of your hair is in this phase at any given time.
3. Telogen phase (resting phase)
Duration: 2 to 4 months. Growth stops, and the hair stays in the follicle without actively growing. Approximately 10 to 15% of the hairs on your scalp are in this phase. At the end of it, the hair is shed to make way for new growth.
4. Exogen phase (shedding phase)
Duration: overlaps with the telogen phase. The old hair is shed from the follicle, and a new hair begins growing in the anagen phase. Shedding is a natural part of the cycle: people lose an average of 50 to 100 hairs per day.
Factors affecting the hair growth cycle
Several factors influence the cycle, leading to variations in growth rate, shedding patterns, and hair loss:
- Genetics. Your genetic makeup plays a significant role in the length and characteristics of your growth cycle. Conditions like androgenetic alopecia (male and female pattern baldness) are inherited and affect growth patterns.
- Hormones. Changes during pregnancy, menopause, or thyroid disorders can affect the cycle. DHT, a derivative of testosterone, shrinks follicles and shortens the anagen phase, leading to thinning and loss.
- Age. As we age, the cycle can slow down, leading to thinner hair and lower density. The anagen phase may shorten while the telogen phase lengthens, increasing shedding.
- Health and nutrition. Deficiencies in essential vitamins and minerals, such as iron, zinc, and biotin, can disrupt the cycle and lead to hair loss.
Shedding vs. hair loss
Losing 50 to 100 hairs a day is a normal part of the exogen phase. Shedding that is noticeably heavier, or hair that grows back thinner, is worth a professional look.
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A free, in-person consultation with an Advanced Hair Restoration® physician looks at your follicles directly and explains where your hair is in its cycle.
Hair transplantation and the hair growth cycle
Hair transplant techniques such as Follicular Unit Extraction (FUE) and Follicular Unit Transplantation (FUT) work within the framework of the growth cycle. Healthy follicles are harvested from the donor area, typically the back and sides of the scalp, and transplanted to balding or thinning areas.
01
Telogen: a temporary shed
It is common for transplanted hairs to enter a temporary telogen phase shortly after the procedure, which leads to shedding. This is a normal part of the process.
02
Anagen: new growth
The transplanted follicles then enter the anagen phase and begin to grow new hair. Success relies on the follicles establishing themselves and producing hair naturally, and new growth typically begins within a few months.
See the full hair transplant timeline and results.
Conclusion
Understanding the hair growth cycle is key to understanding hair loss and how well restoration treatments work. Knowing the phases, and what influences them, helps you make informed decisions about hair care and restoration.
At Advanced Hair Restoration®, we use our in-depth knowledge of the cycle to deliver Advanced FUE™ hair transplants with natural, lasting results.
Questions patients ask
Hair growth cycle questions
What are the 4 stages of hair growth?
Anagen (growth, 2 to 7 years), catagen (transition, 2 to 3 weeks), telogen (resting, 2 to 4 months), and exogen (shedding, which overlaps with telogen).
How many hairs a day is normal to lose?
People lose an average of 50 to 100 hairs per day as part of the exogen phase. It is a natural part of the cycle.
What percentage of hair is in the growth phase?
Approximately 85 to 90% of the hairs on your scalp are in the anagen phase at any given time, about 1 to 2% in catagen, and about 10 to 15% in telogen.
Why does transplanted hair shed after the procedure?
It is common for transplanted hairs to enter a temporary telogen phase shortly after the procedure, which leads to shedding. It is a normal part of the process, and new growth typically begins within a few months.
Real Results
Simple 1 Day Treatment®. Lifetime Results.
Every photo below is a real Advanced Hair patient: Advanced FUE™, their own natural hair, Guaranteed to Grow for Life™.
Kyle M. · 3,000 Advanced FUE™ grafts
Scott H. · 2,500 Advanced FUE™ grafts
Madison T. · 3,300 Advanced FUE™ grafts
AJ S. · 2,500 Advanced FUE™ grafts
Individual results may vary.
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If you are experiencing hair loss, schedule a free consultation with our expert team. Consultations are in person, so a hair loss professional can examine your scalp and donor area directly and map your exact graft count.