Why does our hair fall out?

It almost always starts the same way.

One ordinary morning, without any drama or background music, you look at your pillow and there are hairs. In the shower, more. In the sink, even more. It's not an avalanche, but in your brain it already looks like a horror scene… all the silent alarms go off.

Something's up.

It doesn't hurt, it doesn't itch, it doesn't bleed. But it's unsettling. Because hair shouldn't fall out like this, right? Or should it? And then the big question arises, whispered as if the follicle could hear you: Is this normal, or am I going bald?

Hair loss is not a system failure. In many cases, it's part of the design.

A regulated, predictable, and sometimes misunderstood biological process.

Other times, though, it's a sign that something else is happening beneath the surface.

And as always, science explains it to you.

What exactly is hair and how is it formed?

From a biological standpoint, hair is a mostly inert structure, composed primarily of keratin, a tough protein that also forms nails. The hair you see, touch, and comb every morning is dead. It doesn't feel, it doesn't react, and it doesn't know you're losing it.

The living part is hidden under the skin.

That's where the real protagonist of this story comes into play: the hair follicle.

The hair follicle is a small structure embedded in the skin, a kind of biological microfactory capable of producing hair cyclically. At its base is the dermal papilla, an area rich in blood vessels that supplies oxygen, nutrients, and chemical signals. As long as this papilla is active and healthy, the hair has a future.

The hair that emerges from the surface is called the hair shaft. It's made up of keratinized cells that, during their growth, filled with keratin and then lost their nucleus. In other words, they grew… and died in the process. Nothing dramatic: that's exactly how it's supposed to work.

This detail is key to understanding hair loss.

When a hair falls out, nothing vital is dying. What happens is that the follicle has decided to stop producing that hair at that moment. The shaft detaches and the cycle continues… or not, depending on the context.

And that's where things get interesting.

The hair cycle: why hair is born, grows… and falls out

Hair doesn't grow continuously. It grows in cycles. Each hair follicle functions autonomously, following its own biological clock. That's why we don't lose all our hair at once (thankfully!) and why finding hairs in the shower isn't, in itself, cause for alarm.

This cycle is divided into three main phases.

Anagen phase: when the hair is in production

This is the active growth phase. The cells in the follicle divide rapidly, and the hair grows at a rate of approximately 1 centimeter per month.

On the scalp, this phase can last between 2 and 7 years, depending on genetic and hormonal factors, as well as the overall health of the body. Under normal conditions, approximately 85–90% of hairs are in the anagen phase at any given time.

While a follicle is here, the hair is healthy, strong, and, in principle, has no intention of falling out.

Catagen phase: the transition moment

It's a brief and little-discussed phase. It lasts only a few weeks and acts as a kind of gradual shutdown of the system.

The follicle stops producing hair, shrinks slightly, and detaches from the dermal papilla. It's not hair loss yet, but rather a "this is as far as we go... for now."

Only 1–2% of hair is in this phase under normal conditions.

Telogen phase: when hair loses its grip

Here comes the part we usually notice. In the telogen phase, the hair no longer grows and remains weakly "anchored" in the follicle for about 2-3 months.

At the end of this phase, the hair falls out. Not because it's damaged, but because its cycle has finished. Simultaneously, if everything is going well, the follicle begins a new anagen phase and starts producing a new hair.

In a healthy person, around 10–15% of hair is in the telogen phase. This explains why losing between 50 and 100 hairs a day is considered normal.

So… why do we see hair falling out?

Because the system works.

Daily hair loss is the biological price of having hair that is constantly renewing itself. The problem isn't that the hair enters the telogen phase; the problem arises when too many follicles enter it at once or when they don't properly return to the growth phase.

That's where stress, hormones, genetics, illnesses, or certain medications come into play. But that's another layer of the story.

Hair doesn't fall out for no reason. It falls out because its cycle has ended. And understanding that cycle is fundamental to distinguishing between normal hair loss... and something that requires attention.

How much hair loss is normal and when does it stop being normal?

From a medical standpoint, hair loss is normal. It's part of the hair growth cycle we've already discussed. Under normal physiological conditions, a healthy person can lose between 50 and 100 hairs a day without it indicating anything serious.

The problem is that this number isn't distributed evenly or discreetly. Hair doesn't fall out one strand at a time as if following a carefully choreographed routine. Sometimes it accumulates, and when we see it all together, our brains go into catastrophe mode.

When hair loss falls within the normal range

In general, we speak of physiological hair loss when:

• The loss is progressive and steady, not sudden.
• There are no clear areas of depopulation or thinning.
• The overall volume remains more or less constant.
• It is not accompanied by other symptoms (pain, intense itching, inflammation)

Very common examples:

• Seasonal fall (especially in autumn)
• Hair loss following periods of mild stress
• A temporary increase after washing or brushing (because the hair was already "programmed" to fall out)

Here, the follicle isn't failing. It's simply renewing material.

When hair loss stops being normal

The warning sign is not how many hairs fall out on a particular day, but the pattern over time.

It is important to pay attention when any of these situations occur:

• Sudden and significant hair loss in a few weeks
• Visible decrease in hair volume
• Appearance of lighter areas or widening of the stripe
• Hair that falls out and doesn't seem to grow back over time
• Hair loss accompanied by extreme fatigue, hormonal changes, weight loss, or general disturbances

In these cases, something more than a simple physiological turnover is usually happening. It could be telogen effluvium, incipient alopecia, a hormonal problem, or even a systemic disease.

An important detail that often causes confusion

Excessive hair loss doesn't always mean alopecia. Conversely, some types of alopecia don't involve significant hair loss, but the hair follicle gradually shrinks, producing increasingly thinner and weaker hairs.

Therefore, focusing solely on the number of hairs that fall out can be misleading. What's relevant is what's happening to the follicle in the long term.

Hair loss is not the same as alopecia

One of the most common mistakes is using hair loss and alopecia as if they were synonyms. They are not. And confusing them is often the main source of unnecessary hair anxiety.

From a medical standpoint, hair loss is a phenomenon, while alopecia is a diagnosis. It seems like a semantic distinction, but it completely changes the picture.

Hair loss: the symptom

Hair loss simply describes the fact that hair falls out from the scalp. It can be physiological, temporary, or reactive. In many cases, it is reversible and leaves no lasting effects.

Typical examples:

• Telogen effluvium following stress, illness, or childbirth
• Seasonal fall
• Hair loss associated with correctable nutritional deficiencies
• Hair loss secondary to certain medications

In these scenarios, the follicle remains alive and functional. The hair falls out, yes, but the system is prepared to produce a new one when conditions improve.

Alopecia: the structural problem

Alopecia, on the other hand, involves an alteration of the hair follicle. Here we're not just talking about hair falling out, but about the follicle losing its ability to produce normal hair.

Depending on the type of alopecia, the follicle may:

• To become progressively miniaturized
• To produce increasingly thinner and weaker hairs
• Entering prolonged periods of rest
• Or even be irreversibly destroyed (in scarring alopecias)

In these cases, the problem is not the hair that falls out, but the hair that never grows back.

Why this difference is key

Two people can lose a similar amount of hair each day and yet have completely different situations.
One may be going through a temporary fall with full recovery.
The other may be developing a silent, slow, and progressive alopecia.

In fact, some types of alopecia, such as androgenetic alopecia, don't cause a dramatic hair loss, but rather a gradual thinning of the hair. The hair doesn't fall out suddenly: it becomes finer, shorter, and less visible until it practically disappears.

Therefore, more important than counting hairs in the shower is observing the pattern, its evolution over time, and the behavior of the follicle. The good news is that understanding this difference prevents many misdiagnoses… and quite a few unnecessary scares.

Genetics rules (much more than we'd like)

If there's one question that always comes up when talking about hair loss, it's this : Is this genetic?

The short answer is yes.
The correct answer is yes, but not in the way we usually think.

Genetics plays a huge role in hair health, especially in the most common types of alopecia. But it's not a simple matter of fact or a straightforward inheritance.

Hair inheritance is not a matter of a single gene.

Hair loss, particularly androgenetic alopecia, is a polygenic phenomenon. This means it doesn't depend on a single culprit gene, but rather on the interaction of many different genes, each contributing a small part to the risk.

Some of these genes influence:

• The sensitivity of the follicle to hormones
• The duration of the growth phase
• The rate of follicle miniaturization
• The ability to regenerate hair

The result is not binary (bald / not bald), but a continuum of possibilities.

The myth of looking at the father

For years the idea has been repeated that baldness is inherited only through the paternal line or that it is enough to look at the father or grandfather to know your hair destiny.
The reality is much less comfortable.

Genetic predisposition can come from either side of the family and combine in unpredictable ways. You can have a parent with abundant hair and develop alopecia, or vice versa.

Genetics doesn't copy and paste. It mixes.

Genetics is not inevitable destiny

Having a genetic predisposition does not guarantee that you will lose hair significantly.

Genetics lays the groundwork, but the final result depends on how it interacts with other factors:

• Hormones
• Age
• Stress
• General health status
• Chronic inflammation
• Medication

In other words: genetics loads the gun, but it doesn't always pull the trigger.

Why two people with the same genetics can evolve differently

Even in people with very similar genetic predispositions, hair growth can be completely different. This is because:

• Individual hormonal differences
• Different life stages
• Unequal exposure to physiological stress
• Normal biological variability

That's why some people start losing hair in their twenties and others maintain an acceptable density for decades, even with a shared family history.

Genetics matters a great deal, but it doesn't act alone or immediately. Understanding its role helps us abandon fatalism and interpret hair loss for what it is: a complex biological process, not a sentence written in our DNA.

Testosterone, DHT and the great hormonal misunderstanding

Few things generate as much confusion as this phrase: My hair is falling out because of testosterone.

There's some truth to it... and a lot of dangerous simplification.

Testosterone, on its own, is not the villain of this story. In fact, it is an essential hormone for many bodily functions, in both men and women. The real protagonist here is its most famous (and most misunderstood) derivative: dihydrotestosterone, or DHT.

What is DHT and why does it matter so much?

DHT is formed from testosterone by an enzyme called 5-alpha-reductase. This conversion occurs naturally in various tissues of the body, including the scalp.

DHT has a much higher affinity for androgen receptors than testosterone. In other words, it's more potent. And here's the key distinction:
Not all follicles react the same way to that power.

The problem isn't the hormone, it's the follicle

In genetically predisposed individuals, certain hair follicles are particularly sensitive to DHT. When this hormone acts on them repeatedly over time, a process called follicular miniaturization occurs.

What does this mean in practice?

• The follicle gets smaller
• Each cycle produces thinner and shorter hair.
• The growth phase is shortened
• There comes a point where the hair is no longer visible

It's not a sudden fall. It's a slow and silent retreat.

Why having a lot of testosterone doesn't automatically make you bald

This point is fundamental to debunking myths.
There are people with high testosterone levels who do not develop alopecia, and others with normal or even low levels who do develop it.

The key is not how much testosterone you have in your blood, but:

• How much is converted into DHT
• And, above all, how your follicles respond to that DHT

Therefore, reducing everything to "testosterone causes baldness" is scientifically incorrect. The hormone is the same; it's the sensitivity of the tissue that changes.

And what about women?

Although to a lesser extent, women also produce testosterone and DHT. In women, hormonal imbalances (such as polycystic ovary syndrome or certain hormonal changes with age) can increase androgenic activity on the hair follicle and cause diffuse thinning patterns, especially in the central area of the scalp.

It is not the same type of alopecia as in men, but the hormonal mechanism shares common bases.

The key idea to remember

• Testosterone does not "kill" hair.
• DHT does not act the same way all over the world.
• And androgenetic alopecia is not a hormonal punishment, but an interaction between genetics, hormones and time.

Understanding this allows us to abandon simplistic solutions and focus on the problem from where it really occurs: the hair follicle and its biology, not the demonization of a hormone that, incidentally, the body needs.

Stress, cortisol and hair loss: when the body goes into survival mode

Stress has a nasty habit of popping up in every conversation about health. And in many of them, it's a vague, almost catch-all explanation. But in the case of hair, stress does have a real biological basis. Not symbolic. Not abstractly emotional. Physiological.

When the body perceives a physical or psychological threat, it activates the stress response. The key hormone in this response is cortisol. Its function is clear: to prioritize survival. And when it comes to choosing priorities, hair doesn't make the top ten.

What does cortisol do in the body?

Cortisol mobilizes energy, modifies the immune system, and redistributes resources. All of this is useful in the short term. The problem arises when stress persists over time.

In situations of prolonged stress, the body:

• Reduce non-essential processes
• Systemic inflammation increases
• It alters hormonal and metabolic signals

And the hair follicle, which is metabolically active and demanding, notices the budget cut.

Telogen effluvium: when many follicles agree

The most common mechanism by which stress causes hair loss is called telogen effluvium.

Under intense or sustained stress, a large number of hair follicles prematurely leave the growth phase and enter the telogen phase. The result is not immediate. Hair loss appears between 2 and 3 months after the stressful event.

This explains why:

• The fall can occur when "everything is already going better"
• Many people don't associate stress with hair loss
• The beginning seems abrupt and alarming.

It's not magic. It's delayed physiology.

Emotional stress and physical stress: the same biological language

For the follicle, it doesn't matter if the stress comes from:

• A surgery
• A disease
• An intense emotional loss
• A prolonged period of mental overload

The body doesn't distinguish the origin. It responds the same way. If the stress is sufficient and sustained, the follicle adjusts its cycle.

The good news (because there is one)

In most cases, telogen effluvium due to stress is reversible. The follicle is not structurally damaged. It has simply entered a state of conservation.

When the stress axis normalizes:

• The follicles gradually return to the anagen phase
• Growth is recovering
• The volume improves over time

However, patience is part of the treatment. The follicle doesn't understand rushing or emotional schedules.

The key idea

Stress doesn't kill hair, but it can put the hair factory on pause.

And when too many follicles receive that message at once, hair loss becomes noticeable. Understanding this mechanism avoids unnecessary guilt and helps address the problem from its true source: the physiology of stress, not the shower or the shampoo.

Diseases that can cause hair loss

Hair has an underappreciated quality: it's a fairly reliable biological indicator. It doesn't diagnose on its own, but when something in the body goes wrong, the follicle usually finds out early on… and sometimes tells its story by falling out.

In these cases, hair loss is not the main problem, but a secondary consequence of another, deeper disorder.

Thyroid disorders: when metabolism rules

The thyroid gland regulates the metabolic rate of almost the entire body, including hair follicles. Both hypothyroidism and hyperthyroidism can cause hair loss.

The distinctive feature here is a fall:

• Diffuse
• Persistent
• Accompanied by other symptoms (fatigue, weight changes, intolerance to cold or heat)

The follicle is not irreversibly damaged, but it is functioning abnormally. When the thyroid disorder is corrected, the hair usually recovers gradually.

Autoimmune diseases: when the immune system gets confused

In some autoimmune diseases, the immune system attacks the body's own structures. The best-known example is alopecia areata, where lymphocytes directly attack the hair follicle.

In these cases:

• The fall can be sudden
• Well-defined areas without hair appear
• The scalp usually looks normal.

Although it has a significant visual impact, the follicle is not destroyed. It is inhibited. And that allows for recovery.

Other systemic autoimmune diseases can also present with diffuse hair loss as part of the overall picture.

Chronic diseases and systemic inflammation

Prolonged inflammatory processes (chronic infections, digestive diseases, systemic pathologies...) can alter the capillary cycle.

The logic is simple: when the body is busy managing inflammation, hair growth takes a back seat.

Here, hair loss usually presents as secondary telogen effluvium, not as primary alopecia.

Infections and high fever

A bout of high fever or a significant infection can trigger hair loss weeks later. Not during the illness, but after it seems to have subsided.

Again, this is not a coincidence. It reflects the physiological impact of the event on the hair cycle.

The important message

In most of these cases, the hair isn't the problem, but rather the messenger. Treating the underlying cause is usually much more effective than focusing solely on the hair.

Therefore, when hair loss is accompanied by other general symptoms, it's advisable to look beyond what's visible in the mirror. The hair follicle rarely makes mistakes, but it almost never acts alone.

Nutritional deficiencies and hair loss: iron, zinc and more

When hair starts falling out, the automatic reaction is usually to look in the supplement drawer. Iron, zinc, biotin, collagen—capsules with promising names and pictures of impossibly long hair. The idea is tempting: if something's missing, I'll just add it and that's it.

The reality is a little more uncomfortable.

Nutrition does influence hair health, but not magically or indiscriminately. The hair follicle is a metabolically active and demanding structure. If certain key nutrients are lacking, its function suffers. But if they are present, simply adding more won't make it work better.

Iron: the classic (and rightly so)

Iron is essential for oxygen transport and cellular activity. When there is an iron deficiency, especially in women of childbearing age, the follicle can enter a state of conservation.

The drop associated with iron deficiency is usually:

• Diffuse
• Progressive
• Accompanied by tiredness, paleness, or decreased overall performance

The message here is clear: if there's a deficiency, correcting it helps. But taking iron "just in case" not only provides no benefit, but can also cause unnecessary side effects.

Zinc: small but essential

Zinc is involved in protein synthesis, cell division, and immune function. A deficiency can affect the hair growth cycle and contribute to diffuse hair loss.

It's not the star nutrient for healthy hair, but without it , the system doesn't function properly. Again, the problem arises when it's lacking, not when it's supplemented without medical advice.

Proteins: the building block

Hair is made of keratin. And keratin is made of amino acids.
Very restrictive diets, protein deficiencies, or rapid weight loss can send the follicle a clear message: there is no material to build on.

The result is usually telogen effluvium weeks after the dietary change. Not immediate. Always delayed. Because the follicle is polite, but resentful.

Vitamins: not all, not always

Some B vitamins, vitamin D, and vitamin A are involved in processes related to hair growth. But it's important to emphasize something here: too much can also be a problem.

Especially with vitamin A, high levels can cause hair loss, the exact opposite of what you want.

The most common mistake

It's a mistake to attribute hair loss to a vitamin deficiency without any evidence of a problem. In healthy individuals with a reasonably balanced diet, hair loss is rarely caused by nutritional factors.

And when it is, the body usually gives more clues than just the hair.

The key idea

Nutrition matters. But it matters when there are real deficiencies.
The follicle needs resources, not megadoses.

Before adding supplements, it's worth asking whether something is truly missing. Because, in biology, correcting deficiencies helps; compensating for what's already working doesn't.

Medications that can cause hair loss

When hair starts falling out, almost no one looks in the medicine cabinet. We look in the mirror, at stress, at genetics… but rarely at the package insert. And yet, some medications can alter the hair cycle quite directly by interfering with the biology of the follicle.

How can medications affect hair?

Most medications that cause hair loss do so through a specific mechanism: they force the follicle to enter the telogen phase prematurely. In other words, they bring forward the end of the hair cycle.

The result is usually a drug-induced telogen effluvium:

• Diffuse fall
• Non-scarring
• Generally reversible

Important: This doesn't happen at the start of treatment, but weeks or even months later. The follicle, as always, develops later.

Drugs most frequently implicated

Some of the best-known groups are:

1. Chemotherapy and cancer treatments

Here the mechanism is different. Many chemotherapy drugs affect rapidly dividing cells, and the hair follicle is one of them.

• It can cause anagen effluvium (rapid drop during the growth phase).
• The hair loss is usually intense, but the follicle does not die.
• In most cases, hair grows back after the treatment is completed.

2. Antidepressants and psychotropic drugs

It's not very common, but some antidepressants can trigger telogen effluvium in sensitive people.

It is not a universal or predictable effect, and it is usually dependent on individual susceptibility.

3. Hormonal contraceptives and induced hormonal changes

The problem is usually not the contraceptive itself, but:

• Abrupt changes in formulation
• Treatment suspension
• Variations in hormonal balance

The hair follicle hates rapid changes. And it expresses this by falling out.

4. Anticoagulants, retinoids and other systemic drugs

Some anticoagulants, treatments with vitamin A derivatives, or certain systemic drugs can alter the capillary cycle.

Again: they don't destroy the follicle, but they throw it off its rhythm.

Reversible hair loss vs persistent hair loss

This point is key to avoiding unnecessary panic.

• In the vast majority of cases, drug-induced fall is reversible.
• The follicle is still alive.
• When the body adapts or the treatment is adjusted, the cycle returns to normal.

Only in very specific contexts (prolonged treatments, combination of factors, marked genetic predisposition) can the effect become more persistent.

The most common mistake

Stopping an important medication without consulting a doctor, for fear of hair loss.

From a medical point of view, it is almost always better:

• Confirm whether the drug is actually involved
• Assess risk-benefit
• Adjust dose or alternatives if necessary

Hair usually grows back. General health, however, doesn't always allow for experimentation.

Key points

• Medications are not usually enemies of hair, but they can temporarily alter its cycle.
  
• Drug-induced hair loss is, in most cases, a temporary side effect, not a permanent hair loss.
• Before blaming the shampoo or genetics, it's worth considering the full context. Because sometimes, the follicle isn't protesting... it's simply obeying chemical commands.

Aging: Why hair changes over the years

Aging is not a disease. But it's not harmless to hair either.

As we age, our hair changes. Not only in quantity, but also in quality, thickness, growth rate, and pigmentation. And this doesn't happen all at once or for a single reason: it's the result of several biological processes that occur simultaneously, at different rates in each person.

There is no system failure here. There is cumulative biology.

What happens to the follicle with age

The hair follicle ages just like other tissues. Over time:

• The anagen phase is shortened
  Hair spends less time growing and more time resting. The result: shorter, thinner, and less dense hair.
• The growth rate decreases
  Hair grows more slowly. It's not noticeable in weeks, but it is in years.
• The cellular activity of the follicle is reduced
  The cells that produce the hair shaft divide less efficiently.
• It decreases local vascularization
  Less oxygen and fewer nutrients reach the dermal papilla. Not because the body "doesn't want to," but because it prioritizes other tissues.

All of this occurs even in people without marked genetic alopecia.

Why does hair get thinner with age?

One of the most frequent changes is the progressive thinning of the hair, even without obvious baldness.

This is because:

• The diameter of the hair shaft decreases
• Each cycle produces a hair that is slightly thinner than the previous one.
• Keratinization is less robust

The result isn't always "I'm going bald," but rather " I have less volume." And that difference is important, both clinically and emotionally.

Gray hair: the most visible (and best understood) sign of aging

Gray hair does not appear because the hair falls out, but because it stops producing pigment.

Within the follicle are melanocytes, the cells responsible for producing melanin. Over time:

• Their number is decreasing
• Their activity is reduced
• They eventually disappear from the follicle

When hair grows without melanin, it is white or gray. It's not that the hair "turns white." It's that it is born without color.

This process is strongly influenced by genetics and only slightly by external factors. Stress can accelerate the appearance of gray hair in predisposed individuals, but it is not the cause of the phenomenon.

Aging vs. alopecia: they are not the same

A key point: aging does not necessarily imply hair loss.

• Hair aging can occur without significant loss of density.
• Early hair loss can occur in young people.
• And both processes can occur simultaneously.

Aging affects all follicles diffusely.
Androgenetic alopecia affects specific follicles, in specific areas.

Confusing them leads to misdiagnoses and unrealistic expectations.

Why some people "age better" in terms of hair

The difference between people is not explained by a single variable, but by the sum of several:

• Favorable genetics
• Reduced hormonal sensitivity of the follicle
• Improved vascularization
• Less chronic inflammation
• Fewer accumulated aggressions (chemical, thermal, mechanical)

Hair loss in men and women: similarities and differences

Although we often talk about hair loss as if it were a universal and homogeneous phenomenon, the reality is much more nuanced. Men and women lose hair through mechanisms that share a biological basis, but they manifest themselves differently. And confusing these patterns is one of the reasons why many diagnoses are late… or misdirected.

What men and women have in common

Let's start with what doesn't change according to gender:

• Hair grows in cycles (anagen, catagen, and telogen)
• The hair follicle responds to hormones, genetics, stress, and overall health.
• Telogen effluvium can affect both sexes equally.
• Reactive weight loss (stress, illness, nutritional deficiency) follows the same biological rules

So far, total equality.

The differences begin when hormones and follicular distribution come into play.

The male pattern: less surprise, more predictability

In men, the most common cause of hair loss is male pattern baldness (androgenetic alopecia ).

Its classic characteristics:

• It mainly affects the hairline and the crown.
• It follows fairly recognizable patterns (receding hairline, top thinning)
• It is strongly associated with follicle sensitivity to DHT
• The progression is usually slow but steady.

Here, hair loss isn't always noticeable. Often, what happens is a gradual miniaturization: the hair doesn't fall out all at once, it simply becomes thinner, shorter, and less visible.

That's why many men say: my hair isn't falling out... but I have less and less of it.

And they're usually right.

The female pattern: more diffuse, more treacherous

In women, hair loss usually presents differently:

• Diffuse lightening, especially in the central area
• Progressive widening of the line
• Preservation of the frontal line in most cases
• Fewer "bare" areas and more loss of overall density

Female pattern baldness exists, but it rarely follows the classic male pattern. Furthermore, in women, hair loss is much more frequently influenced by:

• Hormonal changes (pregnancy, postpartum, contraceptives, menopause)
• Iron deficiencies
• Thyroid disorders
• Sustained stress

This sometimes makes the diagnosis less obvious and later.

The big mistake: applying the male model to women

One of the most common mistakes is evaluating female hair loss using male criteria.

In women:

• "Tickets" are not necessary for a problem to exist
• There may be significant loss of density without bald patches
• The emotional impact is usually greater, even if the change is less visible.

And the reverse also occurs:

• Not all hair loss in men is androgenetic alopecia.
• Severe telogen effluvium can be mistaken for the onset of baldness.

Hormones: same molecules, different responses

Both men and women produce testosterone and DHT. The difference lies not so much in the hormone itself, but in:

• The relative amount
• The sensitivity of the follicle
• Balance with other hormones (estrogens, progesterone)

In women, estrogen has a protective effect on the hair follicle. Therefore, periods such as postpartum or menopause, when this balance changes, are critical times for hair health.

Summary of men vs. women

Men and women do not lose hair in the same way, although they share many causes.

• In men, the pattern is usually more localized and predictable.
• In women, it is more diffuse, multifactorial, and easily underdiagnosed.

Understanding these differences is not a minor detail: it is the basis for not confusing reversible hair loss with progressive alopecia, and for applying solutions that make biological sense... not just aesthetic ones.

Because the follicle doesn't understand gender, but it does respond differently to the hormonal context that surrounds it.

Is it possible to recover hair that has fallen out? And gray hair?

This is probably the most important question in the entire article. And also one of the most surrounded by myths.

The short answer is: sometimes yes, sometimes no.
The scientifically correct answer is: it depends on which part of the system is failing.

Because when we talk about hair regrowth, we are actually mixing two different processes:

• Recover hair that has fallen out
• Restoring hair color (gray hair)

And they don't follow the same biological rules.

The golden rule of hair biology

Before going into nuances, it is important to clarify one fundamental idea:

• If the follicle is alive, there is room for action.
• If the follicle is destroyed, there are no miracles.

And this applies to both growth… and color.

Everything else is just marketing in a white coat.

When hair can recover

In many cases, hair loss is reversible because the follicle is not permanently damaged; its cycle has simply been altered.

• Telogen effluvium (stress, illness, postpartum, surgery)
• Correctable nutritional deficiencies (iron, protein)
• Transient hormonal alterations
• Drug-induced fall
• Reversible inflammatory processes

In these scenarios:

• The follicle is still present
• The dermal papilla is intact
• The system can reactivate the anagen phase

Recovery is not immediate. It usually takes months, not weeks. Because the follicle doesn't respond to human anxiety, but to its own biological clock.

When recovery is partial (and slow)

In androgenetic alopecia, the problem is not that the follicle disappears suddenly, but that it gradually miniaturizes.

Here, the realistic goal is usually not to recover everything, but:

• To halt the progression
• Improve the thickness of existing hair
• Prolong the growth phase
• To prevent still viable follicles from crossing the point of no return

The sooner you act, the more leeway you have.
The longer the time passes, the fewer follicles remain in a condition to respond.

When hair cannot recover

There are situations in which the follicle no longer exists as a functional structure.

This happens in:

• Scarring alopecia
• Destructive inflammatory processes
• Irreversible structural damage to the follicle

We're not talking about stimulating, reactivating, or awakening anything here. We're talking about the absence of biological tissue.

In these cases, no shampoo, supplement, laser, or massage will bring back hair where there is no longer a follicle. The only real options are surgical or cosmetic.

 

And gray hair… can it be recovered?

It is important to be especially clear here.

Gray hair appears because the follicle stops producing melanin. Not because the hair ages externally, but because the melanocytes in the follicle lose activity or disappear.

And this makes the key difference.

Can gray hair regain its pigmentation?

• If the melanocytes have disappeared, no: the process is irreversible.
• If melanocytes are still present but inactive, in theory yes, but it is rare and limited.

In current clinical practice:

• There is no proven treatment that reliably reverses established gray hair.
• "Anti-gray hair" supplements have not shown any real effectiveness
• Stress can accelerate the appearance of gray hair, but it doesn't usually reverse it when it disappears.

There is ongoing research on the role of oxidative stress, inflammation, and mitochondrial metabolism of the melanocyte, but for now, gray hair is, in most cases, a point of no return.

The important nuance

The fact that a gray hair does not grow back does not mean that the follicle is dead.
That follicle can continue to produce hair... only without color.

That's why it's possible to have:

• Gray hair with good density
• Gray hairs that grow normally
• Healthy gray hair, from a structural point of view

The problem here is not growth, but pigmentation.

The big mistake: putting everything in the same bag

One of the most common mistakes is thinking that:

• Hair loss
• Alopecia
• White hair

They are variations of the same problem. No, they are not. Each has different mechanisms, different prognoses, and different margins for action.

The summary

• Hair can grow back if the follicle is alive
• The fall is often reversible.
• Gray hair, in general, is not

Not due to a lack of willpower in the body, but due to real biological limitations.

Why we lose more hair in autumn (and why it's not an ancient mystery)

Every autumn it's the same. The ground is covered in leaves, the light fades… and the shower drain seems to have made a pact with your scalp. The feeling is so common that many people see it as an ancient omen: “That's it, I'm going bald this year.”

Scientific spoiler alert: there's no ancient mystery. There's fairly well-documented seasonal biology.

Seasonal fall exists (and it's not an urban legend)

Autumn hair loss is a real phenomenon, described in clinical studies and consistently observed in human populations. In most cases, it is seasonal telogen effluvium.

It's not that the hair "gets damaged", it's that many follicles synchronize their cycle.

What really happens in the follicle

During the summer, a greater proportion of follicles remain in the anagen (growth) phase. This appears to be related to:

• Increased exposure to sunlight
• Changes in circadian rhythms
• Possible effect of vitamin D and other hormonal signals

As summer draws to a close, some of these hair follicles enter the telogen phase in a coordinated manner. And since the telogen phase lasts about 2–3 months, visible hair loss appears… in autumn.

Does this happen to everyone?

No. And this is also important.

The seasonal decline:

• It is more evident in people with long hair
• It's more noticeable if there's pre-existing density (because there's more hair to fall out)
• It may go unnoticed in other people

And pay attention to this key nuance: seasonal hair loss does not distinguish between men and women, nor between people with or without previous alopecia.

Is it dangerous? Does it leave lasting effects?

In a healthy person, no.

Seasonal telogen effluvium:

• It is self-limiting
• It does not destroy the follicle
• It does not, on its own, lead to alopecia

Hair usually recovers spontaneously in the following months, provided there are no other contributing factors (intense stress, nutritional deficiency, illness, active androgenetic alopecia).

The most common mistake

Attempting to aggressively treat a normal seasonal hair loss.

This is where they appear:

• Unnecessary supplements
• Compulsive product changes
• Treatments initiated without indication
• And a lot of gratuitous hair anxiety.

Biology doesn't usually need intervention when everything is working as it should.

Key ideas

Hair loss in autumn:

• It's real
• It is physiological
• It's temporary
• And it has nothing mystical about it

It's not the inevitable start of baldness. In most cases, it's the price you pay for having had a great summer for your hair.

Frequently asked questions about hair loss

Is it normal to lose hair every day?

Yes. Hair is constantly renewing itself, and daily hair loss is part of the normal hair cycle (anagen, catagen, and telogen). Losing some hair daily is not a sign of illness in itself.

How many hairs normally fall out per day?

In most healthy people, losing between 50 and 100 hairs a day is within the normal range.

Does washing your hair cause more hair to fall out?

No. When you wash your hair, you're simply removing hairs that were already in the telogen phase (ready to fall out). If your hair is long or you haven't washed it for several days, you'll see more hair at once, and it will feel more dramatic.

Can stress cause hair loss?

Yes. The most typical mechanism is telogen effluvium: many follicles prematurely enter the resting phase, and visible hair loss usually appears 2–3 months after the period of stress (physical or emotional). In most cases, it is reversible.

Does testosterone cause baldness?

Not directly. The main culprit is usually DHT (dihydrotestosterone) and, above all, the genetic sensitivity of certain hair follicles to that hormone. You can have high testosterone and not develop alopecia, or have normal levels and still develop it.

Is hair loss hereditary?

Androgenetic alopecia (the most common type) has a strong genetic component and is polygenic (involving many genes). But genetics is not destiny: the final outcome also depends on age, hormones, inflammation, overall health, and other factors.

Does hair grow back after it falls out?

It depends. If the follicle is alive (for example, in telogen effluvium), the hair usually grows back. If the follicle has been destroyed (as in certain types of scarring alopecia), there is no spontaneous regeneration.

Does diet influence hair loss?

Supplementation is only effective when there are actual deficiencies (iron, protein, zinc, etc.). If there's no deficiency, supplementing "just in case" rarely improves hair and can sometimes cause problems. The hair follicle needs sufficient nutrients, not megadoses.

Which vitamins are related to hair loss?

Vitamin D and some B vitamins may be involved in certain situations, but the key issue is deficiency. Furthermore, an excess of some vitamins (such as vitamin A) can also contribute to hair loss. It's best to measure and adjust accordingly.

Why does more hair fall out in autumn?

Because there is a seasonal component to the hair cycle: many follicles synchronize their entry into the telogen phase after summer, and hair loss becomes more noticeable in autumn. It is usually temporary and does not necessarily imply alopecia.

Can hair loss be a symptom of an illness?

Yes. Thyroid disorders, some autoimmune diseases, serious infections, chronic inflammation, or systemic problems can disrupt the hair follicle cycle. If hair loss is accompanied by other general symptoms, a medical evaluation is warranted.

Can medications cause hair loss?

Yes, some medications can trigger telogen effluvium (diffuse and reversible hair loss), and cancer treatments can cause more severe hair loss by affecting rapidly dividing cells. It is never advisable to stop medication without consulting a doctor.

Does wearing hats or helmets cause baldness?

It does not cause androgenetic alopecia. At most, extreme use with friction, sweat, and constant tension could irritate or weaken the hair shaft (breakage), but that is not the same as permanent hair loss.

Does long hair fall out more than short hair?

It's not necessarily that more hair falls out: it's just more noticeable. Long hair takes up more visual space and accumulates in the shower/brush, so the "psychological impact" increases even if the actual amount is similar.

Is hair loss different in men and women?

Yes. In men, a localized pattern (receding hairline/crown) is more typical due to androgenetic alopecia. In women, it tends to be more diffuse (widening of the part), with a greater relative influence of iron, thyroid function, and hormonal changes.

Do emotional and physical stress affect hair equally?

From a biological perspective, yes: the hair follicle responds to stress as a physiological signal, whether it comes from surgery, a high fever, or an intense emotional period. The typical pattern is delayed hair loss weeks or months later.

Is it possible to stop hair loss?

It depends on the cause. In reversible hair loss, treating the trigger (stress, deficiency, illness, medication) usually leads to improvement. In androgenetic alopecia, acting early helps slow progression and preserve follicles before they miniaturize too much.

Does hair loss mean I'm going to go bald?

No. A lot of visible hair loss can be telogen effluvium (reversible), and some types of alopecia progress without noticeable hair loss (more like thinning). What's important is the pattern over time: density, bald patches, and progression.

When should I see a doctor about hair loss?

When hair loss is sudden and heavy for weeks, there is a visible loss of density, bald patches appear, it is accompanied by itching/pain/inflammation, or there are general symptoms (fatigue, weight loss, menstrual irregularities, etc.). If it does not improve over time, it is also a cause for concern.

What types of alopecia exist?

There are several types. The most common is androgenetic alopecia (genetic and hormonal). Others include telogen effluvium (diffuse and reversible hair loss), alopecia areata (autoimmune), and scarring alopecias, where the hair follicle is irreversibly destroyed.

How does a hair transplant work, and does it really work?

The transplant involves moving hair follicles resistant to hair loss (usually from the back of the head) to areas with thinning hair. It works if the transplanted follicle survives and the biological context is suitable, but it does not stop existing hair loss or create new hair where there are no follicles.

Why do you go bald on your head but not on your back or other areas?

Because the hair follicles on the scalp have different hormonal sensitivities. Those in the frontal and crown areas respond to DHT, while those in the nape of the neck, beard, or back are not affected by this hormone.

Does wearing a hat cause more hair to fall out?

No. Wearing a hat does not cause androgenetic alopecia or destroy hair follicles. Only in extreme cases of constant friction could it break the hair shaft, but that does not equate to permanent hair loss.

Why does hair fall out first at the temples and not all over the scalp?

Because the hair follicles at the temples and crown are genetically more sensitive to DHT. This difference in sensitivity explains why hair loss follows specific patterns and doesn't affect the entire scalp equally.