Hair Growth and Hair Loss: How Hair Grows, and Why It Falls Out
Losing between 50 and 100 hairs a day is completely normal, because at any moment around nine in ten of the hairs on your scalp are actively growing while the rest are resting or being shed. Hair loss becomes real when that balance tips, when more follicles switch off than switch on, or when the growing phase gets shorter with each cycle. Understanding the cycle is the whole point, because the pattern of your shedding, how fast it came on, and where it is thinning are what separate ordinary shedding from something worth treating, and the same thinning can be driven by genetics, by an iron or thyroid problem, by stress or by age, each of which has a different answer. At The Wellness London the approach begins with working out which of those is happening before anyone recommends a treatment, and the first step is our free Hair Health Check.
Medically reviewed by a GMC-registered doctor at The Wellness London. Last updated August 2026.
Start with the free Hair Health Check. It takes a few minutes, a doctor reviews your answers, and you get a personalised summary by email telling you what your shedding is likely pointing to and what could help. Take the Hair Health Check: https://www.thewellnesslondon.com/forms/hair-health-check
At a glance
Every follicle moves through a growth phase, a short transition, and a resting phase before the hair is shed and replaced, and healthy hair depends on most follicles being in the growth phase at once. Hair loss happens when follicles spend less time growing, miniaturise over successive cycles, or shift in large numbers into shedding. The commonest drivers are genetic pattern loss, temporary shedding after a stress on the body, nutritional deficiency, thyroid and hormonal changes, and the natural effect of age. Whether hair grows back depends almost entirely on whether the follicle is still alive, which is why finding the cause early matters more than any single product.
How the hair growth cycle works
Each hair on your head is produced by a follicle that runs on its own clock, independent of its neighbours, which is why you are always growing some hairs and shedding others rather than moulting all at once. The growth phase, called anagen, is the long one, lasting roughly two to six years, and it is what determines how long your hair can get before it is shed. The longer your anagen, the longer your hair grows.
After anagen the follicle enters a brief transition phase of a couple of weeks, then a resting phase called telogen that lasts around three months, at the end of which the old hair is released and a new hair begins to push through underneath. On a healthy scalp the great majority of follicles are in anagen at any given time, a small proportion are resting, and only a fraction are shedding, which is the balance that keeps hair looking full. Hair loss, in almost every form, is a story about that balance being disturbed.
Normal shedding, or hair loss?
Seeing hairs on your pillow, in the shower drain or on your brush is not in itself a sign of a problem, because shedding is the normal end of the cycle. What matters is the trend over weeks and months. Ordinary shedding stays roughly steady, the hair regrows, and the overall density holds. Hair loss shows up as a widening part, a scalp that is more visible in bright light, a ponytail that feels thinner, a receding hairline, or handfuls of hair coming out noticeably faster than before.
The speed and pattern are the clues a doctor reads. Slow, gradual thinning in a recognisable pattern points one way, a sudden heavy shed a few months after an illness, birth or period of stress points another, and patchy loss or an itchy, sore or scarred scalp points somewhere else entirely. This is exactly the information the Hair Health Check is designed to capture, so the picture is clear before any treatment is discussed.
Why hair falls out: the main causes
Genetic pattern hair loss is the most common cause in both men and women. Here the follicle is sensitive to hormones and shrinks a little with each cycle, producing finer, shorter hairs until it stops altogether, which is why it is gradual and follows a pattern rather than coming on overnight.
Temporary shedding, known as telogen effluvium, is the next most common, where a shock to the body pushes an unusually large number of follicles into the resting phase at once, and they shed together two to three months later. Childbirth, a high fever or illness, surgery, crash dieting, significant stress and stopping or starting hormones can all trigger it, and the reassuring part is that it usually recovers once the trigger has passed.
Nutritional and medical drivers are the ones most often missed. Low iron stores, thyroid problems, vitamin D deficiency and hormonal conditions all thin the hair diffusely, and they are common and treatable, which is why a good assessment looks underneath the scalp rather than only at it. Add to these the effects of tight hairstyles and chemical treatments, certain medications, and inflammatory or scarring scalp conditions, and it becomes clear why a single cause cannot be assumed.
Not sure which of these fits you? The Hair Health Check asks the questions a doctor would and turns your answers into a personalised summary. Start it here: https://www.thewellnesslondon.com/forms/hair-health-check
How age changes hair growth
Age affects hair in its own right, separately from pattern loss. As the years pass the growth phase tends to shorten, follicles produce finer strands, the rate of regrowth slows, and pigment-producing cells wind down, which is why hair often becomes thinner, drier and greyer over time even without a strong genetic pattern. In women this frequently overlaps with the hormonal shift of menopause, and in men it compounds the steady progression of pattern loss.
None of this means thinning with age is untreatable. It means the plan has to be realistic and matched to what the follicle can still do, because the earlier hair is assessed, the more there is to work with. Acting while follicles are only miniaturising, rather than gone, is the single biggest thing within your control.
Can hair grow back?
The honest answer is that it depends on the follicle. Where the follicle is still alive but underperforming, as in early pattern loss, temporary shedding or a correctable deficiency, hair can recover and thicken, sometimes substantially. Where the follicle has been lost, as in long-established bald areas or scarring conditions, regenerative and medical treatments can protect and thicken what remains but cannot regrow a bald scalp, and a transplant becomes the honest conversation.
This is why a diagnosis-first approach matters so much in hair. The same product can transform one person and do nothing for another, and the difference is usually the cause and the timing, not the product. Testing the cause before treating it is what turns a course of treatment into a result rather than a gamble.
How a doctor-led assessment finds the cause
A proper hair assessment starts with your story, the pattern and speed of the loss, your family history, your health, medications and any recent triggers, and then, where indicated, blood tests to check the treatable drivers such as iron and ferritin, thyroid function, vitamin D and relevant hormones. Only once the cause is clear does treatment make sense, whether that is correcting a deficiency, a prescription such as minoxidil or finasteride where appropriate, or a regenerative option such as PRP.
Our free Hair Health Check is the first step in exactly this pathway. It gathers the same information a doctor would ask for, our medical team reviews it, and you receive a personalised summary of what your hair loss is likely pointing to and the sensible next steps for you.
Take the first step today. Complete the free Hair Health Check and get a doctor-reviewed summary by email: https://www.thewellnesslondon.com/forms/hair-health-check
Frequently asked questions about hair growth and hair loss
How much hair loss a day is normal?
Losing roughly 50 to 100 hairs a day is normal and is simply the end of the natural cycle. What matters is whether your overall density is holding steady or falling over weeks and months, and whether the hair is regrowing.
How can I tell shedding from real hair loss?
Shedding stays fairly constant and the hair regrows, while hair loss shows as a widening part, a more visible scalp, a thinner ponytail or a receding hairline over time. A sudden heavy shed a few months after a trigger usually points to temporary telogen effluvium.
Will my hair grow back?
If the follicle is still alive, as in early pattern loss, temporary shedding or a corrected deficiency, hair can recover. Where follicles are lost, treatment thickens and protects what remains rather than regrowing a bald area, so acting early gives the best chance.
Does hair really thin with age on its own?
Yes. With age the growth phase shortens and strands become finer and slower to regrow, separately from genetic pattern loss, and in women this often overlaps with menopause. It can still be supported, and earlier assessment means more to work with.
What is the first thing I should do about hair loss?
Work out the cause before choosing a treatment. Our free Hair Health Check captures the information a doctor would need and gives you a personalised, doctor-reviewed summary by email.
Your next step
The most useful thing you can do about hair loss is understand what is driving yours, because that is what decides whether it can be recovered and how. Our free Hair Health Check is quick, it is reviewed by a GMC-registered doctor, and it ends with a personalised summary sent to your email.
Take the free Hair Health Check now: https://www.thewellnesslondon.com/forms/hair-health-check
This article is for information and does not replace personal medical advice. Hair loss has many causes and results vary between individuals. Assessment and any treatment at The Wellness London are carried out by GMC-registered doctors. Reviewed by a GMC-registered doctor at The Wellness London. Last updated August 2026.
References. Standard dermatology literature on the hair growth cycle and normal daily shedding. Published literature on androgenetic alopecia, telogen effluvium and diffuse hair loss. Published literature on iron, ferritin, thyroid function and hair. Published literature on ageing and the hair follicle.
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