Many people worry when they see more hair than usual on their brush or pillow. Yet losing between 50 and 100 hairs a day is completely normal. Sudden, heavy shedding, bald patches or gradual thinning, however, are worth investigating, because the treatment depends entirely on the cause.

Why does hair fall out? The most common causes

1. Temporary shedding after a shock to the body

After a high fever, surgery, childbirth, intense stress or a strict diet, many hairs enter their resting phase at the same time and fall out two to three months later. The shedding is spread across the whole scalp, usually stops on its own, and the hair grows back within months.

2. Hereditary hair loss (androgenetic alopecia)

This is the most common cause. In men, it starts with a receding hairline or thinning at the crown. In women, it shows as diffuse thinning, especially along the parting, while the front hairline is kept. It progresses slowly over years.

3. Alopecia areata

Round, hairless patches appear suddenly on the scalp or in the beard. The cause is immune-related and it is not contagious. It sometimes improves on its own and responds to treatments prescribed by a dermatologist.

4. Medical causes revealed by a blood test

  • Iron deficiency, especially in women.
  • Thyroid disorders (underactive or overactive thyroid).
  • Some medicines: never stop a medicine without talking to your doctor.

5. Causes linked to hair or scalp care

Hairstyles that are constantly tight (braids, ponytails), frequent heat styling and chemical treatments, or scalp ringworm, a fungal infection that mostly affects children and causes scaly patches.

What tests might the doctor order?

The doctor starts with questions: when the shedding began, whether it is diffuse or patchy, whether it followed a fever, childbirth or stress, what medicines you take, and whether you have other symptoms such as tiredness or irregular periods. They then look at the pattern of hair loss. Depending on the case, they may order a blood test including iron stores and thyroid function, and sometimes hormone tests in women.

Which treatments actually work?

Rule number one: treat the cause. Correcting an iron deficiency or balancing the thyroid is often enough to stop the shedding.

  • Hereditary hair loss: there are topical treatments, applied to the scalp, with proven results in men and women, and oral treatments available on prescription for men. Your doctor chooses what suits you after assessing your situation and discussing side effects.
  • Alopecia areata: topical treatments or injections given by a dermatologist, depending on how widespread the patches are.
  • Temporary shedding: often needs no medicine, just patience and a balanced diet, with treatment of any deficiency found.

Supplements only help if there is a real deficiency. Oils and home mixtures may improve how hair looks, but they don't treat the cause of hair loss.

When should you see a doctor?

  • Sudden, heavy shedding, or shedding that lasts more than three months.
  • Bald patches appearing.
  • Redness, itching, pain or flaking on the scalp.
  • Hair loss with tiredness, weight change, irregular periods, or acne or excess facial hair in women.
  • Hair loss in a child.

See a dermatologist

In most cases, a dermatologist can assess hair loss in a video consultation, order the right tests and prescribe treatment. You can book an appointment and choose the doctor and time that suit you.