Anagen Phase: How the Hair Growth Cycle Actually Works
The anagen phase is the active growing stage of the hair cycle, and it is the single thing that decides how long and how thick a hair can get. On the scalp it lasts two to seven years, which is why scalp hair reaches your shoulders while an eyelash never does. At any moment roughly 85 to 90 per cent of your hair should be in anagen. When that percentage drops, you shed more and the hair that grows back is finer. Most of what people call slow growth is really a shortened anagen phase, and the levers that genuinely influence it are your general health, your iron and protein intake, your stress load, and how gently you handle the hair you already have.
Key Takeaways
- Anagen is the growing phase. Two to seven years on the scalp, about a month on lashes and brows. Its length is mostly genetic and it sets your maximum hair length.
- Hair grows about 1cm a month. That rate barely varies between people. What varies is how long each hair keeps going before it stops.
- 85 to 90 per cent of your hair should be growing right now. Shedding of 50 to 100 hairs a day is normal and is not a sign anything is wrong.
- Big shedding events are usually delayed. Illness, childbirth, surgery, crash dieting or a severe stress period push hairs into resting early, and you see the result two to three months later.
- You cannot lengthen anagen with a cosmetic product. What you can do is remove the things shortening it, and stop losing length to breakage, which is what most people are actually experiencing.
- Judge nothing before three months, and properly at six. Anything promising faster than that is not describing biology.
What is the anagen phase?
Each follicle on your head works independently, on its own schedule, cycling through three stages for your whole life. Anagen is the first and by far the longest.
During anagen, cells in the hair matrix at the base of the follicle divide faster than almost any other cells in the body. They push upward, keratinise, and become the hair shaft. As long as the follicle stays in anagen, the hair keeps getting longer at a fairly fixed rate of roughly one centimetre a month, or about six inches a year.
This is why the length question has a simple answer. If your anagen phase runs for two years, your maximum length is around 24cm. If it runs for seven, you can reach waist length. Neither is better or worse, and no product moves you from one group to the other. Understanding that saves you from buying things sold on a promise that biology does not support.
The three phases and how long each one lasts
| Phase | What happens | How long | Share of your hair |
|---|---|---|---|
| Anagen (growing) | The follicle actively builds hair shaft, about 1cm a month | 2 to 7 years on the scalp | 85 to 90% |
| Catagen (transition) | Growth stops, the lower follicle shrinks back | 2 to 3 weeks | 1 to 2% |
| Telogen (resting) | The hair sits in place, held loosely, then sheds | About 3 months | 10 to 15% |
Some researchers add a fourth stage, exogen, which is simply the moment of release when the old hair falls and a new anagen hair is already pushing up beneath it. That detail matters for one practical reason: seeing a shed hair does not mean you have lost that follicle. In a healthy cycle the replacement is already on its way.
How much shedding is normal?
Fifty to one hundred hairs a day. That figure surprises people, because a hundred hairs looks like a lot when they are gathered in a shower drain.
Two things distort the picture:
- Wash frequency. If you wash twice a week rather than daily, the hairs that were ready to release on the days in between all come out at once. Three days of normal shedding looks alarming in a single handful. It is not three days worth of extra loss.
- Hair length and colour. Long dark hairs on a light bathroom floor are simply more visible than short fair ones. Nothing has changed except how easily you notice.
What genuinely warrants attention is a sustained change: noticeably more shedding than your own normal for more than six to eight weeks, a parting that is visibly wider in photographs, or a ponytail that has lost real thickness. Those are worth investigating. A dramatic drain after a week away from washing is not.
Why hairs leave the growing phase early
A shortened anagen phase almost always has a cause, and it is usually not on your shelf. The common ones:
- A physical shock two to three months ago. Illness with a high fever, COVID, surgery, general anaesthetic, childbirth or a period of severe undereating pushes a large batch of follicles into resting at the same time. You see the shed months later, which is why people rarely connect the two. This is telogen effluvium, and it is usually self limiting.
- Iron deficiency. Low ferritin is one of the most common findings in women in the UK with diffuse shedding, and it is easily checked with a blood test.
- Thyroid changes. Both an underactive and an overactive thyroid disrupt the cycle.
- Sustained low protein or rapid weight loss. Hair is a low priority tissue and it is cut off early when the body is rationing.
- Chronic stress. Prolonged elevated stress hormones are associated with hairs entering the resting phase prematurely.
- Hormonal shifts. Pregnancy, stopping or starting hormonal contraception, and the perimenopausal transition all change the picture.
- Genetic sensitivity in androgenetic hair loss. Here anagen shortens progressively cycle by cycle, and hairs come back finer and shorter each time until they no longer break the surface. This one is patterned rather than diffuse.
If you want the full picture on the delayed shedding pattern, our guide to what causes telogen effluvium covers the triggers and the recovery timeline, and can stress cause hair loss looks specifically at the stress link.
What you can and cannot influence, ranked honestly
This is the section most articles avoid, because the honest ranking puts products near the bottom.
| Lever | Strength of evidence | What it realistically does |
|---|---|---|
| Correcting a genuine deficiency (iron, protein, vitamin D, thyroid) | Established | Removes the thing shortening anagen. The most reliable change available, and it needs a blood test rather than guesswork |
| Medical options via a doctor | Established for some conditions | A conversation for you and a qualified professional. We are a cosmetic company and cannot advise on it |
| Reducing breakage: gentler washing, conditioning, heat protection, looser styles | Strong for length retention | Does not change the cycle, but it is why most people never see the length their anagen phase allows |
| A comfortable, well looked after scalp | Reasonable | Persistent itching, flaking and inflammation are worth resolving in their own right, and scratching causes mechanical damage |
| Scalp massage | Limited | Small studies only, but it is free, pleasant and carries no downside |
| Supplements when your diet is already adequate | Weak | Topping up something you are not short of does very little. Useful only where intake is genuinely low |
Notice what is missing from that table: any cosmetic product claiming to extend the growing phase. Shampoos and serums are cosmetics. They work on the hair fibre and the scalp surface, and a good one earns its place by reducing breakage and keeping the scalp comfortable. That is a genuinely useful job, and it is not the same job as changing the cycle.
The distinction worth holding on to: anagen length decides how long your hair can get. Breakage decides how long it actually gets. Almost everyone has more room to gain on the second than on the first.
Grow Me® Hair Growth Shampoo
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Looking after the environment the follicle sits in
You cannot instruct a follicle. You can make the surface it lives in a more comfortable place, and there is a sensible version of this that avoids both extremes of neglect and obsession.
- Wash often enough. The idea that frequent washing causes loss is a myth. Build up of oil, sweat, dry shampoo and styling product leaves the scalp itchy, and scratching does real mechanical damage. Wash when your scalp needs it.
- Massage while you wash. One to two minutes with the pads of your fingers, not your nails. Free, and the evidence, while limited, points one direction.
- Condition the mid lengths and ends every wash. This is a length retention decision, not a vanity one. Hair that snaps at 15cm never shows you what your anagen phase was capable of.
- Take the tension out. Tight ponytails, buns and braids worn daily cause traction damage along the hairline that becomes permanent if it goes on for years. Vary where the tension sits.
- Turn the heat down. Use a protectant and the lowest setting that does the job. Most straighteners run far hotter than anyone needs.
- Detangle from the ends upward, on damp rather than soaking wet hair, with a wide tooth comb.
Grow More® Leave-In Density Serum
An overnight leave-on scalp elixir with biotin, caffeine, rosemary, niacinamide and allantoin. Designed for lower density areas such as the crown and the parting, where you want a fuller looking finish and a comfortable scalp.
£25.50 · leave-in, vegan, made in the UK
If breakage is your real problem, and for most people with fine or colour treated hair it is, the conditioning step matters more than anything else you buy.
Condition Me® Hair Growth Conditioner
Breakage defence with cholesterol, shea butter, glycerin, hydrolysed lupine protein and silica. Detangles so combing pulls less, which is where a surprising amount of everyday length is lost.
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Nutrition and the growing phase
Hair matrix cells divide extremely fast, which makes them unusually sensitive to whatever the body is short of. This is why hair is often the first visible sign that something nutritional is off, and why correcting a real shortfall produces such a clear response.
The ones that matter most:
- Protein. Around 0.8g per kilogram of body weight daily as a baseline, more if you are very active. Consistently below that and hair thins across the board.
- Iron and ferritin. Ferritin is the storage form and it is the number worth asking about. It can be low while a standard full blood count still reads as normal.
- Vitamin D. Commonly low in the UK from October through March.
- Zinc. Involved in the structural side of hair formation. Do not self supplement heavily, as too much interferes with copper absorption.
- B vitamins including biotin. These contribute to the maintenance of normal hair when intake is adequate. Genuine biotin deficiency is rare on a normal diet, which is why supplementing it in someone who is not short of it does very little.
Food first, testing before supplementing, and a supplement only to fill a gap you have actually identified. That order saves money and works better.
How long before you can judge anything?
The cycle sets the timetable, and nothing shortens it. Here is what to expect if you change something today.
- Weeks 0 to 6. Nothing visible. Anything you notice in this window is how your hair is behaving, not new growth. This is where most people give up.
- Months 2 to 3. If a shedding event was triggered by something months back, it should be settling now. Shedding often gets slightly worse before it improves as resting hairs release together.
- Months 3 to 4. Short new hairs appear along the parting and hairline. They stick up and refuse to lie flat, which is a good sign rather than an annoyance. At 1cm a month they are only 3 or 4cm long.
- Months 6 to 9. Density starts to look different in photographs rather than in your own perception. This is the first honest assessment point.
- Month 12. A full picture. New hairs are now 12cm and blended in.
Take a photograph in the same place, in the same light, on the first of every month. Human memory is hopeless at judging gradual change, and the photographs will tell you something your mirror cannot.
What the cycle explains about different kinds of hair loss
Telogen effluvium. A large batch of follicles moves into resting at once after a trigger, then sheds together two to three months later. Diffuse, all over, and in most cases it recovers on its own once the trigger has passed. This is the pattern behind postpartum hair loss, which is one of the most common versions and one of the most reliably temporary.
Androgenetic hair loss. Genetically sensitive follicles shorten their anagen phase progressively, cycle after cycle. Each new hair comes back a little finer and a little shorter until it no longer reaches the surface. It is patterned rather than diffuse, at the crown and temples in men and along the parting in women, and it is gradual over years. Our page on what causes thinning hair goes through how to tell the patterns apart.
Alopecia areata. An autoimmune condition in which the immune system interrupts follicles in the growing phase, producing smooth, well defined patches. This one is medical, it is not something a shampoo has any bearing on, and it needs a doctor. Please see your GP rather than working through products.
When to speak to your GP
Get a proper opinion, and ask about a blood panel including ferritin and thyroid function, if you notice:
- Heavier than usual shedding that has continued beyond eight weeks
- Smooth, round, well defined bald patches
- Any redness, scaling, pain, burning or scarring of the scalp
- Shedding alongside fatigue, weight change, low mood or changes to your periods
- Sudden loss across the scalp, brows and body hair together
- Any hair loss in a child
None of these mean something serious is happening, and all of them are questions a GP can answer far faster than the internet can.
Frequently asked questions
How long is the anagen phase?
Two to seven years on the scalp for most people, which is why maximum hair length varies so much between individuals. Eyelashes and eyebrows run a much shorter growing phase of about 30 to 45 days, which is why they stay short no matter what you do. The length of your anagen phase is largely inherited.
Can you make the anagen phase longer?
Not with a cosmetic product, and you should be sceptical of anything claiming otherwise. What you can do is remove the things shortening it, such as low iron, low protein, thyroid problems or a period of severe stress, and stop losing the length you do grow to breakage. For most people the second is where the visible gain actually is.
What percentage of hair is in the anagen phase?
Around 85 to 90 per cent at any given moment, with 10 to 15 per cent resting and a small remainder in transition. When a larger share moves into resting at once, you get the heavy shedding of telogen effluvium, typically two to three months after whatever triggered it.
Is losing 100 hairs a day normal?
Yes. Fifty to one hundred a day is the normal range, and it looks like far more than it is when it gathers in a drain or on a hairbrush. If you wash a few times a week rather than daily, several days of shedding arrive at once, which is why wash day always looks alarming.
How fast does hair actually grow?
About one centimetre a month, or roughly six inches a year, and that rate is remarkably consistent between people. Nothing meaningfully speeds it up. The reason two people have very different hair length is the duration of their growing phase and how much they lose to breakage, not the speed.
Why does new hair stick straight up?
Because it is new. Hairs entering the growing phase after a shedding event are short, fine and have not yet gained the weight to lie flat. Seeing a halo of short hairs along your parting or hairline is generally a good sign, even though it looks untidy. They will settle as they lengthen.
Does scalp massage do anything?
The evidence is limited but points in a positive direction, and it costs nothing, feels good and carries no risk. Use the pads of your fingers rather than your nails, for one to two minutes while you wash. Think of it as a small helpful habit rather than the centre of a routine.
Will cutting my hair make it grow faster?
No. Growth happens at the follicle and the follicle has no idea what is happening at the other end. What a trim does is remove split ends before they travel up the shaft, which stops you losing length to breakage. That is why regular trims often make hair seem to grow better, even though the rate has not changed.
Watermans products are 100% cosmetic and do not treat medical hair loss. Individual results may vary.
Where to start
Work down the list in order of effect. Ask your GP for a blood test if shedding has been going on for more than a couple of months, because correcting a real deficiency is the most reliable change available to anyone. Then take the mechanical losses out of your routine: gentler detangling, lower heat, looser styles, conditioner every wash. Then, and only then, think about products, and expect them to do the cosmetic job they honestly do rather than a biological one they cannot.
If you want a straightforward daily pairing while you work through the rest, Grow Me® Shampoo and Condition Me® Conditioner are the two most people start with. Watermans has sold over 5 million bottles since 2012, and every formula is vegan and made in the UK.
