Hair loss: why it happens and what to do

Losing hair every day is normal: up to about 100 hairs a day is part of the natural hair cycle. It becomes a concern when hair loss clearly increases over weeks, when the hair becomes thinner or when bald patches appear.

The two most common causes are a temporary shedding triggered by a "shock" to the body, such as childbirth, an illness or a diet, and androgenetic alopecia, of genetic and hormonal origin. The first usually resolves on its own within months; the second is progressive, but can be treated with medicines of proven effectiveness. The first step is always to understand which case is yours.

How much hair is normal to lose

Each hair goes through three phases:

• Growth (anagen): lasts about 2 to 6 years. About 85% of hairs are in this phase.
• Transition (catagen): a few weeks.
• Resting (telogen): about 3 to 4 months, at the end of which the hair falls out and is replaced. About 15% of hairs are in this phase.

That is why losing up to about 100 hairs a day is normal (DermNet). On the days you wash your hair, the loss seems greater, because the loose hairs that have built up come out all at once.

Signs that hair loss has gone beyond normal:

• clumps on the pillow, in the drain or on the brush, repeatedly for weeks;
• a visibly thinner ponytail;
• a wider parting or more visible scalp, especially on top;
• a receding hairline or a thinner crown;
• round bald patches.

The most common causes

1. Telogen effluvium: hair loss after a "shock"

An event that overloads the body can push up to 70% of growing hairs into the resting phase at the same time (DermNet). The shedding appears 2 to 4 months after the event, which is why many people do not make the connection.

Common triggers: childbirth, illness with fever (including viral infections), surgery, intense stress, rapid weight loss or restrictive diets, iron deficiency and some medicines.

The shedding is diffuse, across the whole scalp, and does not cause complete baldness. In most cases it returns to normal 6 to 9 months after the cause is removed. When it lasts longer than 6 months, it is called chronic telogen effluvium and deserves investigation.

2. Androgenetic alopecia: the most common in the long term

It has a genetic and hormonal origin. Follicles that are sensitive to androgens gradually produce hairs that are thinner and shorter. It affects about 50% to 60% of men by age 50 and up to 40% of women by age 70 (Kanti et al., European S3 guideline).

• In men: a receding hairline and a thinner crown.
• In women: a wider central parting and less volume on top, while the frontal hairline is kept.

It starts gradually and is progressive. The earlier it is treated, the more hair is preserved.

3. Other causes to know about

It is common to have more than one cause at the same time: for example, an effluvium after childbirth that makes visible an androgenetic alopecia that was just starting.

How the diagnosis is made

The diagnosis is mainly clinical, but it requires a method:

1. Medical historyWhen it started, events in the previous 2 to 4 months, medicines, diet, menstrual cycle, family history.
2. Examination and pull testGently pulling a lock of hair shows whether the shedding is active.
3. TrichoscopyA dermatoscope magnifies the scalp and shows hair thickness and signs of miniaturisation, inflammation or scarring. The European guideline recommends it in cases of doubt (Kanti et al.). Learn more in Trichoscopy: the examination that shows the scalp.
4. Blood tests, when indicatedAs a rule: full blood count, ferritin, thyroid function and, depending on the case, vitamin D, zinc or hormones. We go into detail in Blood tests for hair loss: what to ask for.
5. BiopsyRarely needed; reserved for suspected scarring alopecia or doubtful cases.

Treatments: what has evidence

Treatment depends on the cause. In telogen effluvium, the essential step is to identify and correct the trigger, for example iron deficiency or a low-protein diet; the hair grows back on its own. In androgenetic alopecia, there are treatments with efficacy shown in clinical trials. Choose who the treatment is for to see only the options that apply to you.

What you should know before you start

• Patience. Results are assessed at 6 months, and the peak is around 12. In the first weeks of minoxidil there may be a temporary increase in shedding, a sign that the hairs are renewing.
• Continuity. In androgenetic alopecia, the gains are lost months after stopping treatment.
• Side effects. Minoxidil can cause irritation or facial hair growth. Finasteride can cause sexual side effects and, in 2025, the European Medicines Agency confirmed suicidal thoughts as a possible side effect, of unknown frequency. Anyone taking it should stop and contact their doctor if mood changes occur (EMA, 2025).
• Pregnancy. Finasteride and dutasteride are contraindicated in women who could become pregnant without effective contraception.

All medical treatments require assessment and a prescription.

What you can do at home

• Eat enough protein and a varied diet. Hair is made of keratin, a protein. See Diet and hair loss: what the hair strand needs.
• Do not take supplements blindly. They only help when there is a deficiency. An excess of vitamin A or selenium can even cause hair loss.
• Treat your hair gently: loose hairstyles, less heat from dryers and straighteners, careful brushing.
• Photograph your scalp every 3 months, always with the same light and the same angle. It is the best way to tell whether it is getting worse or better.
• Sleep well and manage stress. Intense stress is a known trigger of effluvium.

Common myths

When to seek a medical assessment

Book an appointment if:

At Luxmed, the Hair Medicine consultation includes a detailed medical history, trichoscopy and, when indicated, blood tests, to find the cause before proposing any treatment.

This article is for information only and does not replace a medical consultation.

Frequently asked questions