Hair loss in women: the most common causes and what to do

Is it normal to lose hair every day?

Yes.

Hair has its own biological cycle. Each follicle goes through growth, transition, and resting phases, and eventually the hair falls out to be replaced by a new one.

That is why losing approximately 50–100 hairs per day can be considered physiological.

The problem arises when we notice a change from our usual situation: much greater shedding, progressive loss of density, an increasingly visible centre parting, or certain areas of the scalp that are beginning to thin out.

And here a very important distinction comes into play.

Shedding and loss of density do not necessarily mean the same thing.

You may lose a great deal of hair over a few months and then recover it afterwards. But you may also lose relatively few hairs and yet notice them becoming progressively finer due to follicular miniaturisation.

These are different mechanisms and they require different diagnoses.

What are the most common causes of hair loss in women?

When we look into the types of alopecia in women, we find very different situations.

Among the most common are telogen effluvium and female androgenetic alopecia, but many other possibilities exist.

1. Telogen effluvium: when large amounts of hair suddenly fall out

It is one of the situations that frightens people the most.

The patient begins to find large amounts of hair in the shower, on the brush, on the pillow, or on their clothing.

And very often the trigger did not happen yesterday.

Telogen effluvium usually appears weeks or months after an event that has disrupted the hair cycle.

It can occur after a serious illness or fever, a surgical procedure, rapid weight loss, certain physiologically stressful situations, some medications, or after pregnancy, among other circumstances.

In many cases the follicle is not destroyed.

Simply put, an abnormally high number of hairs have simultaneously entered the phase of the cycle that will end in shedding.

That is why it is essential to identify the context before assuming we are dealing with permanent hair loss.

2. Female androgenetic alopecia: when hair becomes progressively thinner

Female androgenetic alopecia is another very important cause of hair loss.

Here the problem can be more subtle.

Women do not always report dramatic shedding. What they notice is that they progressively have less density, the central parting widens, or the scalp becomes more visible.

The affected follicles progressively produce finer and shorter hairs.

This phenomenon is called follicular miniaturization.

Female androgenetic alopecia can begin before menopause and become more noticeable with age. There is a genetic predisposition, although we do not always find clear family history.

And the earlier we identify it, the sooner we can consider strategies aimed at preserving the still-active follicles.

3. Could iron be deficient?

Yes, but with an important nuance.

When we investigate hair loss in women, we must assess the clinical and nutritional context.

In certain patients, iron deficiency may be present, especially in those with heavy periods, specific dietary restrictions, or other causes of iron loss or reduced iron availability.

For this reason, when there is clinical suspicion, blood work may include parameters that allow a proper assessment of iron metabolism.

However, this does not mean that every woman experiencing hair loss needs to take iron supplements.

Supplements should only be used when there is a clear indication.

4. What about the thyroid?

Thyroid disorders can also be associated with changes in hair and diffuse hair loss.

Depending on the clinical history and associated symptoms, evaluating thyroid function may be warranted.

Again, the goal is not to indiscriminately order dozens of tests.

The physical examination and clinical history guide us toward what we should be looking for.

5. Hormones, menopause, and polycystic ovary syndrome

Hormones can also play a role.

In some women with androgenetic alopecia, signs of hyperandrogenism may coexist, such as menstrual irregularities, acne, or increased body hair.

In those cases, we need to assess whether an underlying hormonal imbalance is present, as may occur in certain patients with polycystic ovary syndrome.

Menopause can also alter the hormonal balance and make a pre-existing predisposition to hair density loss more apparent.

But again: having female androgenetic alopecia does not automatically mean having a hormonal problem.

6. Hair loss after pregnancy

Postpartum hair loss deserves a separate explanation because it can be quite striking.

During pregnancy, hormonal changes modify the hair cycle, and many women notice thicker, fuller hair.

After delivery, many of those hairs shift in a relatively synchronized manner toward the phases that will end in shedding.

The result can be significant hair loss a few months later.

In the majority of cases, this is a temporary phenomenon.

However, if the loss persists or density does not recover as we would expect, it is worth checking whether another cause of alopecia is simultaneously present.

Can there be two causes at the same time?

Yes.

And this point is especially important.

A patient may have a relatively mild female androgenetic alopecia and subsequently experience a telogen effluvium.

The sudden shedding then makes a loss of density that was already developing slowly far more visible.

That is why we should not always have to choose between: 'It is stress' or 'It is androgenetic alopecia.'

In some patients, both conditions can coexist.

How do we evaluate hair loss in women?

Everything begins with a thorough clinical history.

We need to know when it started, whether the shedding was sudden or gradual, whether there is a family history, any changes in weight, recent illnesses, surgical procedures, pregnancy, medications, menstrual characteristics, and other possible triggers.

Next, we examine the hair and scalp.

A particularly useful tool is trichoscopy.

Using magnification, we can observe characteristics of the follicle and hair shaft that cannot be properly appreciated with the naked eye.

This helps, for example, to detect signs of miniaturization compatible with androgenetic alopecia and to differentiate it from other conditions.

When indicated, we can complete the assessment with blood tests.

And in certain less common situations, a scalp biopsy may even be necessary.

What treatments for hair loss can be used in women?

There is no universal answer because treatment depends on the diagnosis.

If telogen effluvium is present, we must identify and correct the trigger whenever possible.

If a proven deficiency exists, we must correct it.

If we are dealing with an inflammatory disease or a scarring alopecia, we need to treat that disease.

And when we diagnose female androgenetic alopecia, we have a range of therapeutic options available.

One of them is minoxidil, which we have already discussed specifically in another article in El médico te explica.

Depending on each patient and the diagnosis, other medical strategies may be considered.

But the goal should not be to accumulate treatments.

It should be to choose the right treatment for the right cause.

Do hair vitamins actually work?

This is probably one of the questions we hear most often.

Advertising has managed to create an almost automatic association: hair loss in women = hair vitamins.

But medically, it doesn't work that way.

If a nutritional deficiency exists, correcting it is important.

But if no deficiency exists, indiscriminately taking iron, zinc, biotin, or other supplements does not necessarily solve the problem.

And more supplements do not mean more hair.

That is why, before starting months of capsules, we need to ask ourselves whether there is truly something we need to supplement.

When should you seek medical advice?

I would recommend an evaluation when we notice hair loss that is clearly greater than usual and persists, a progressive decrease in density, a widening part, areas with no hair, or symptoms affecting the scalp.

We should also pay particular attention when pain, inflammation, significant flaking, or signs that may suggest scarring alopecia appear.

In these cases, an early diagnosis is especially important because certain conditions can cause irreversible destruction of the hair follicle.

What I want you to remember

When we talk about hair loss in women, one of the most common mistakes is trying to treat it before diagnosing it.

Vitamins. Shampoos. Serums. Minoxidil. Everything can start before anyone has stopped to ask what is actually happening.

But the most important question remains the same: Why is your hair falling out?

Because behind hair loss in women there may be a completely reversible transient phenomenon, female androgenetic alopecia, a deficiency, a medical condition, or a disease specific to the hair follicle.

First we diagnose. Then we treat.