Hair Growth Cycle: Anagen, Catagen, Telogen and Exogen

What is the Hair Growth Cycle?

The hair growth cycle refers to the natural process through which hair grows, rests, sheds, and regenerates. Each hair strand on the scalp goes through this cycle independently, ensuring that not all hair falls out at once. Understanding these phases helps in maintaining hair health and managing hair loss effectively.

What are the 4 Phases of the Hair Growth Cycle?

The hair growth cycle consists of four distinct stages:

1. Anagen Phase (Growth Phase)
   • The longest phase, lasting 2 to 7 years.
   • Around 85-90% of hair is in this stage at any given time.
   • Hair grows actively as follicles produce new cells.
2. Catagen Phase (Transition Phase)
   • Lasts about 2-3 weeks.
   • Hair follicles shrink, and growth slows down.
   • Hair detaches from the blood supply but remains in place.
3. Telogen Phase (Resting Phase)
   • Lasts around 3-4 months.
   • Hair remains attached but does not grow.
   • New hair begins forming beneath the old hair.
4. Exogen Phase (Shedding Phase)
   • Old hair strands fall out to make way for new ones.
   • Normal shedding is about 50-100 hairs per day.
   • The cycle then restarts with new anagen-phase hair growth.

1. Anagen: Growing Phase

The anagen phase is the first stage of hair development. It is the longest phase, lasting roughly 3 to 5 years for the hairs on your head, yet a single hair may continue to grow for 7 years in certain people. Fortunately, the anagen period varies amongst hair types. During the anagen phase, your hair follicles produce hairs that will grow until they are clipped or reach the end of their lives and fall out.

2. Catagen: Transition Phase

The catagen phase begins when the anagen phase ends and lasts roughly 10 days. Hair follicles atrophy and hair development slow during this chapter. The hair also splits from the hair follicle's bottom. At any given moment, only around 5% of the hairs on your head are in the catagen phase.

3. Telogen: Resting Phase

The telogen period usually lasts 3 months and affects around 10% to 15% of your scalp hairs. Hair does not grow during the telogen period, but it also does not fall off. In addition, new hairs begin to grow in follicles that have recently produced hairs during the catagen phase during the telogen phase.

4. Exogen: Shedding Phase

The exogen phase of hair development is simply an extension or component of the telogen stage. Hair is lost from the scalp during the exogen phase, which is typically aided by washing and combing. It is common to lose 50 to 100 hairs every day throughout the exogen period. During the exogen phase, which can last between 2 and 5 months, new hairs develop in the follicles while old hairs fall out.

What Influences Hair Growth Cycles?

Several factors affect how long each phase lasts and the overall health of the hair growth cycle, including:

• Genetics: Determines the length of the anagen phase.
• Age: Hair growth slows down over time.
• Nutrition: Protein, vitamins (biotin, vitamin D), and minerals (iron, zinc) play a crucial role.
• Hormones: Imbalances in testosterone, estrogen, or thyroid hormones can affect growth cycles.
• Scalp Health: Proper care and hydration support a healthy cycle.

What Can Disrupt the Hair Growth Cycle?

Certain conditions can cause an imbalance in the natural hair cycle, leading to excessive hair loss or thinning:

• Stress and lifestyle habits
• Poor diet and vitamin deficiencies
• Hormonal imbalances (e.g., thyroid disorders, pregnancy)
• Excessive heat styling or chemical treatments
• Medical conditions like alopecia or scalp infections

How to Extend the Hair Growth Cycle?

Prolonging the anagen phase can help maintain fuller, healthier hair. Here’s how:

• Maintain a balanced diet with protein, vitamins, and minerals.
• Use scalp treatments like essential oils or minoxidil.
• Reduce stress through meditation, exercise, and sleep.
• Avoid excessive heat styling and harsh chemical treatments.
• Consider PRP therapy or medical treatments for hair loss prevention.

Delayed Growth After A Hair Transplant

Here is how the hair transplant timeline takes place: Typically, all the transplanted hair is lost in an effluvium and enters a resting period after a transplant. Assume that an FUE slow growth is a novel phenomenon associated with the implantation of extremely tiny hair grafts. In such instances, the hair development cycle in tiny grafts may react differently to the shock of transplanting than those in bigger grafts. In other words, the desiccation, temperature change, and mechanical damage to which tiny grafts may be more susceptible induce a delay in development in circumstances when the follicle was not entirely destroyed. Of course, if you want to learn how to speed up hair growth after the hair transplant, you should consult your doctor before applying any method.

How many hair growth cycles does each hair follicle undergo in a lifetime?

Each follicle undergoes about 20-25 hair growth cycles throughout a person’s lifetime. However, the length of each cycle varies depending on genetics and overall health.

How much hair shedding is normal during the hair growth cycle?

On average, shedding 50-100 hairs per day is considered normal as part of the exogen phase. If shedding exceeds this range for an extended period, it may indicate an underlying issue like stress, hormonal imbalance, or nutritional deficiency.

About ASMED

At ASMED Surgical Medical Center, we inspire people to look and feel their best by using the most advanced FUE hair transplant (Follicular Unit Extraction) digital technology for scalp analysis and Coverage Value calculations available in the field of hair restoration today. We are dedicated to patient education, innovation, and delivering life-changing results. At ASMED, we continue to pioneer new surgical approaches to ensure the best outcomes for our patients.