Everyone sheds—adults do it, kids do it… everyone with hair sheds. But how do you know what’s normal and what’s not when it comes to shedding?

Understanding the biology of the hair growth cycle is essential for identifying patterns of shedding, thinning, or hair loss. Let’s break down each phase of the cycle, what influences it,  and how you can achieve healthier hair growth.

What is the hair growth cycle?

Did you know that the scalp contains approximately 100,000 hair follicles, each cycling independently through the hair growth cycle? The hair growth cycle is the natural process your hair goes through as it grows, rests, and finally sheds to make room for new strands. 

It has four main phases: anagen (growth), catagen (transition), telogen (rest), and exogen (shedding).

The majority of your scalp hairs are in the anagen phase at any given time (approx. 85-90%), which is when they grow. After that, they gradually stop growing, rest, and then fall out so new hair can grow in its place. 

Phase 1: Anagen—the growth phase

This first phase, anagen, is the active growth phase of your hair cycle. This phase usually lasts anywhere from 2-7 years, depending on factors like your genetics, age, and overall health. During this time, your hair follicles are hard at work producing new strands thanks to a flurry of cell activity in the base of the follicle (aka the matrix). At any given time, about 85–90% of the hairs on your scalp are in this growth mode.

Have you ever wondered why some people seem to grow long, flowing hair effortlessly while others struggle to get past shoulder-length? The answer is found in this phase of the hair growth cycle, and how long you stay in it.

If you have a longer anagen phase, you’ll be able to grow your hair longer before it naturally sheds and starts over. But if your anagen phase is short, your hair just won’t grow the same length—even if it's healthy and doesn't break easily.

One condition that affects this cycle is called Short Anagen Syndrome (SAS). It’s a rare but harmless disorder (often linked to certain genetic or nutritional conditions) where the growth phase is unusually shortened. As a result, hair may look thin, shed more often, and rarely grow beyond a certain point.

The good news? There are ways to combat this. Treatments like Minoxidil are thought to prolong the anagen phase for both men and women, and increase the size of your hair follicles, potentially leading to fuller, longer hair over time.

Phase 2: Catagen—transition phase

This second phase of the hair growth cycle is a transition phase and lasts around 10-14 days. During this time, the lower portion of the hair follicle regresses and begins to break down. This process is driven by apoptosis, which is just a fancy way to say programmed cell death. 

As the follicle regresses, it detaches from the blood supply that causes it to grow. Eventually, this hair will fall out during the telogen phase to make room for a new hair to grow in its place.

Why does this phase matter? Even though it only lasts a short time, the catagen phase is a necessary reset step before the hair enters a rest phase. Without this controlled shutdown, your hair wouldn’t be able to cycle properly. Disruptions in this process can contribute to miniaturization in androgenetic alopecia.

Phase 3: Telogen—resting phase

The telogen phase is the resting stage of the hair cycle and typically lasts around 3 months, though the exact length can vary depending on your age and health. At any given time, about 10–15% of your hairs are in telogen.

While the hair stops growing during the previous catagen phase, because of apoptosis, the strand remains held in place during telogen. 

So what’s happening behind the scenes? A new hair begins forming beneath the old one and will eventually push it out during the next phase.

Phase 4: Exogen—shedding phase

Although it was only recognized as its own phase fairly recently, exogen is the stage when your hair actually sheds from the follicle—separate from the telogen phase. This is when the old hair is released and makes room for a new one to grow in its place.

It’s important to remember that shedding is normal, but not constant. It tends to follow a cyclical pattern, and seasonal changes can play a role too. So if you're noticing a bit more hair showing up in the shower or on your brush during certain times of year, it doesn’t automatically mean something’s wrong or that you’re balding—it could just be that your hair has hit the exogen phase of the hair growth cycle.

What can disrupt the hair growth cycle?

While the hair growth cycle usually runs smoothly, certain health factors can throw it off course. These disruptions can lead to increased shedding, thinning, or slower growth. Here are some of the most common causes:

1. Telogen effluvium: stress-induced hair loss

Telogen effluvium happens when a large number of hair follicles suddenly shift from anagen (the growth phase) to telogen (the resting phase), leading to noticeable shedding within a few months. It can be triggered by physical or emotional stress, such as:

• High fevers or illness 
• Nutrient deficiencies, especially low iron, zinc, or protein
• Rapid weight loss or crash diets
• Medications like antidepressants, beta blockers, or retinoids

Luckily, this type of hair loss is usually temporary—once the stressor is resolved, the cycle typically resets.

2. Androgenetic alopecia: hormone-driven hair thinning

Also known as male or female pattern hair loss, this condition is driven by sensitivity to DHT (a hormone derived from testosterone). Over time, DHT causes hair follicles to shrink, leading to shorter growth phases and thinner hair. This type of hair loss is usually gradual and progressive.

3. Autoimmune or inflammatory conditions

Conditions like alopecia areata or lupus can also disrupt the hair cycle. In these cases, the body’s immune system mistakenly attacks hair follicles, leading to patchy or more widespread hair loss. Treatment often involves managing the underlying inflammation or immune response.

How can I maintain a healthy hair growth cycle?

Oral supplements and medications

The first step is to nourish from within. Supplements, such as protein, iron, vitamin D, biotin, and zinc are excellent ways to maintain a healthy hair growth cycle. Randomized trials have also shown nutraceuticals with multi-nutrient complexes to have very promising results. Oral medications may also help support the hair growth cycle. 

As part of Shed’s new Hair lineup, we’re launching two oral medication options for men and one for women. These medications are designed to support a healthy hair growth cycle from the inside out. These options combine powerful ingredients, like biotin and minoxidil, to help nourish every phase of the hair growth cycle.

Topical solutions

Topical treatments can play a key role in maintaining a healthy hair growth cycle. Some of the topical therapies include: 

• Prescription strength minoxidil
• Natural DHT blockers like saw palmetto and caffeine
• Shed’s very own topical solutions for men and women. These topical solutions offer  multi-ingredient formulas designed to target hair thinning and promote the appearance of thicker, healthier-looking hair. 

Lifestyle

And lastly, lifestyle changes can go a long way in supporting a healthy hair growth cycle. Chronic stress can elevate cortisol levels, which has been linked to follicular regression and increased shedding, so finding ways to relax can be super helpful. Prioritizing good sleep, incorporating scalp massages to boost circulation, and avoiding harsh chemicals or excessive heat styling can all help create a healthier environment for your hair to grow and thrive.

When should I be worried about how much I’m shedding?

It might be time to talk to your doctor if you’re experiencing any of the following:

• Shedding over 150 hairs/day consistently
• Widening part or visible scalp
• Sudden onset of patchy hair loss
• History of autoimmune disease 
• Recent trauma or illness

These symptoms may be a sign of a bigger health issue that should be addressed with a medical professional.

Shedding is normal

Shedding is a natural part of the hair growth cycle, not something to fear. Understanding the rhythm of anagen, catagen, telogen, and exogen can help you tune in to what your body (and your hair) might be trying to tell you and recognize when your body is asking for extra support. At Shed, we’re here to help by connecting you with a licensed provider that can determine what treatment might be best for you. Not only that, we’ll help you with expert education, and ongoing support to keep your follicles flourishing.

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Resources: 

1. Blume‑Peytavi et al., 2011 – Scalp Hair Follicle Biology
(Referenced for ~100,000 follicles & 85–90% in anagen)

• Ulrike Blume-Peytavi, Hair Growth and Disorders, Springer, 2008 [via Wikipedia summary] self.com+5en.wikipedia.org+5allure.com+5.
  
  

2. Harrison & Sinclair, 2002 – Telogen Effluvium Review
(Referenced for telogen effluvium causes and rates)

• S. Harrison & R. Sinclair, Telogen effluvium. Clinical and Experimental Dermatology, 2002 27:389-395. en.wikipedia.org+15pmc.ncbi.nlm.nih.gov+15skin.dermsquared.com+15
  
  

3. Mieczkowska et al., 2020 – COVID‑19 Induced Telogen Effluvium
(Referenced for COVID-19 as trigger for telogen effluvium ~1–3 months later)

• K. Mieczkowska et al., Telogen effluvium: a sequela of COVID‑19. International Journal of Dermatology, 2021 60(1):122–124. self.com+9onlinelibrary.wiley.com+9pmc.ncbi.nlm.nih.gov+9
  
  

4. Rossi et al., 2021 – Case Series on Post‑COVID TE
(Referenced for proposed mechanisms and timing of shedding)

• A. Rossi et al., Telogen Effluvium after SARS‑CoV‑2 Infection: A Series of Cases..., Skin Appendage Disorders (2021) pmc.ncbi.nlm.nih.gov+8pmc.ncbi.nlm.nih.gov+8allure.com+8europepmc.org+15karger.com+15pmc.ncbi.nlm.nih.gov+15
  
  

5. Self.com & Allure – General COVID‑19 Hair Loss Coverage
(Referenced for prevalence and timeline)

• Hair Loss After COVID-19 Is Still Happening—Here’s How Long It Lasts, Self.com, May 2022 allure.com+3self.com+3self.com+3
  
  
• You're Not Imagining It: The Pandemic Is Triggering Stress‑Induced Hair Loss, Allure, Nov 2020 allure.com+1self.com+1

6. Wikipedia – Human Hair Growth & Hair Follicle Overview
(Phases: anagen, catagen, telogen, exogen; growth rates; follicle anatomy)

• Human hair growth & Hair follicle Wikipedia entries (updated regularly) reddit.com+6en.wikipedia.org+6en.wikipedia.org+6
  
  

7. Harkey, 1993 – Definition of Exogen Phase
(Referenced via Wikipedia summaries)

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