Hair loss: causes, diagnosis and treatments

When is hair loss normal?

Our hair is continuously renewing itself. Each hair follicle goes through different phases of growth, transition, and rest before the hair finally falls out.

Losing approximately 50–100 hairs per day can be part of this normal physiological cycle.

Therefore, finding a few hairs in the shower does not necessarily mean that there is alopecia.

What should draw our attention is a change from our usual situation: a much more abundant loss, a progressive decrease in density, a parting that keeps getting wider, a receding hairline, or the appearance of clearly thinning patches.

Why does hair fall out?

Hair loss can be due to numerous factors and, in some people, several causes may coexist.

Telogen effluvium

It is a frequent cause of diffuse hair loss.

It can appear a few months after an event that has disrupted the body: an illness, a significant fever, surgery, childbirth, substantial weight loss, or stressful situations, among other circumstances.

In many cases, when the trigger disappears, the hair cycle gradually returns to normal.

Androgenetic alopecia

It is the most common form of hereditary alopecia and can affect both men and women.

In men, it typically manifests progressively with a receding hairline and loss of density in certain areas of the scalp. In women, it is common to observe a progressive decrease in density and a widening of the parting.

Early detection is important because treatment can slow its progression and, in certain patients, improve hair density.

Alopecia areata

It usually produces well-defined hairless areas and has an autoimmune origin: the immune system attacks the hair follicle.

Its presentation, progression and treatment differ from those of androgenetic alopecia.

Nutritional deficiencies and medical conditions

In certain patients, hair loss may be related to iron or other nutrient deficiencies, thyroid disorders, certain hormonal imbalances, systemic diseases or some medications.

This does not mean that everyone experiencing hair loss needs an extensive battery of tests. The clinical history and physical examination help determine when blood work is truly indicated.

Traction and repeated trauma

Hairstyles that place significant and sustained tension on the hair can cause traction alopecia. If this trauma is maintained over a long period of time and permanently damages the follicle, the hair loss may become irreversible.

Hair loss in women: is it different?

The search for 'hair loss in women' is common, and it makes sense to address it specifically.

In women, we must consider, among other possibilities, telogen effluvium, female androgenetic alopecia, certain hormonal imbalances, possible nutritional deficiencies, thyroid diseases and other dermatological causes.

Furthermore, a patient may present more than one underlying mechanism simultaneously. For example, telogen effluvium can make a previously unnoticed androgenetic alopecia more apparent.

For this reason, automatically attributing all female hair loss to stress or vitamin deficiencies can delay the correct diagnosis.

How do we evaluate hair loss?

The first step is not to choose a shampoo or start a supplement.

The first step is to make a diagnosis.

During the consultation, we assess how the hair loss began, how long it has been progressing, whether it is diffuse or localised, family history, recent illnesses, medications, diet and other possible triggers.

Next, we examine the scalp and hair.

Trichoscopy, which allows the scalp and follicles to be examined under magnification, can provide very useful information for differentiating between the various types of alopecia.

Depending on the findings, blood tests may be requested and, in specific situations, other tests such as a scalp biopsy.

Treatment for hair loss: what really works?

This is probably the most important question.

And the answer is: it depends on the cause.

Telogen effluvium is not treated the same way as androgenetic alopecia. Alopecia areata requires a different approach. And an iron deficiency must be corrected if it genuinely exists, but giving iron to someone who does not have a deficiency is not a universal treatment for hair loss.

What about minoxidil?

Minoxidil is one of the best-known treatments for certain types of alopecia and has evidence supporting its ability to promote growth and reduce the progression of hair loss in appropriately selected patients.

But it is not a universal treatment either.

Furthermore, results take time: in the indications where it is effective, improvement is typically assessed over the course of months and the benefit depends on maintaining the treatment.

We will dedicate an upcoming article in The Doctor Explains exclusively to minoxidil, because there are important differences between its indications and the ways in which it is used.

Do vitamins and hair-loss capsules work?

Hair-loss capsules and supplements are very popular, but it is important to distinguish between marketing and genuine medical need.

If a nutritional deficiency is responsible for or aggravating the hair loss, correcting it is important.

However, taking supplements indiscriminately is no substitute for a proper diagnosis. In fact, an excess of certain nutrients can also be harmful, and some excesses have been linked to hair loss.

That is why I do not recommend automatically treating every case of hair loss with vitamins without first asking ourselves why the hair is falling out.

When should we seek a consultation?

A dermatological assessment is advisable when hair loss persists, clearly increases, there is a progressive loss of density, there are completely bare patches, or it is accompanied by scalp abnormalities.

Early assessment is also warranted for hair loss that raises suspicion of cicatricial alopecia, because in this group of conditions inflammation can permanently destroy the follicle, and the primary goal is to prevent further loss.

The idea I want you to remember

When a patient asks me: 'Doctor, what can I take for hair loss?', my first question is not which product to recommend. It is: 'Why is your hair falling out?'

Because hair loss is not a diagnosis.

Correctly identifying the cause is what allows us to decide whether we simply need to observe, correct a trigger, run blood tests, or start a specific treatment.

And the sooner we identify certain types of alopecia, the greater our chances of preserving the follicle and the existing hair.