What Is telogen effluvium?

Most hair on the scalp grows actively during the anagen phase, which typically lasts 2–4 years. After this, hair enters a resting phase (known as telogen) for 2-4 months, before the hair falls out to be replaced by a new one. It is normal for a person to lose up to 100 hairs per day on average.

In telogen effluvium (TE), more hairs than usual enter the resting phase, leading to increased shedding. Instead of losing up to 100 hairs daily, some people may lose up to 300 hairs a day, resulting in noticeable thinning of hair volume.

What causes telogen effluvium?

Common triggers include:

• Surgery or physical trauma
• Psychological stress
• High fever, infection, or illness
• Changes in diet or rapid weight loss, including from using weight loss drugs
• Hormonal changes, such as following childbirth
• Iron deficiency
• Thyroid disorders (hypothyroidism or hyperthyroidism)
• Certain medications

Hair loss usually appears 2–4 months after the triggering event. In about 30% of cases, the exact cause of TE cannot be identified.

What does telogen effluvium look like?

Telogen effluvium presents in the following ways: 

• Hair sheds diffusely across the scalp, rather than in patches
• Hair may feel thinner and you may notice more hairs falling out than usual
• Hair loss can be alarming, but most hairs that enter the resting phase are gradually replaced by new growth

How is telogen effluvium diagnosed?

Diagnosis of telogen effluvium is usually made by a dermatologist through:

• Medical history and scalp examination
• Hair pull test – gently tugging hair to see how many hairs come out
• 24-hour hair collection – sometimes used to measure hair shedding
• Blood tests – to check for thyroid problems, iron deficiency, or other underlying conditions

How long will telogen effluvium last?

TE typically resolves within 6–9 months as the hair cycle returns to normal. Hair volume recovery depends on hair length and individual factors

Can telogen effluvium be treated?

Most cases do not require treatment; hair usually regrows once the trigger is resolved. Supportive measures such as gentle hair care, a balanced diet, and stress management can aid recovery

In some cases where hair regrowth is incomplete, your dermatologist may recommend topical minoxidil, which can stimulate hair growth in some individuals

Additional Information:

The British Association of Dermatologists (BAD) has produced a Patient Information Leaflet for telogen effluvium.

READ THE BAD PATIENT INFORMATION LEAFLET ON TELOGEN EFFLUVIUM

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