HOI Encyclopedia Category: Hair Loss Disorders

Anagen Effluvium

Written by HOI Medical Editorial Team
Medically reviewed by Dr. Mahmut Satekin
First published: September 2026 · Last updated: September 2026

Anagen effluvium is sudden hair loss caused by an insult severe enough to halt cell division in actively growing follicles, so the shaft breaks rather than shedding normally. It appears within days to weeks, most often after chemotherapy or radiotherapy, and is usually reversible.

Key Facts

Phase affected Actively growing hairs
Timing Days to a few weeks after the cause
How it comes out Broken shaft with no club root
Main causes Chemotherapy and radiotherapy
Extent Can approach total loss
Recovery Usual once the cause is removed

Anagen effluvium hits the hair while it is still growing. An insult severe enough to stop cell division in the bulb interrupts the shaft mid-production. The hair does not complete its cycle and release normally — it fractures at the weakened point and breaks off, often within days to a few weeks of the cause.

Anagen effluvium Telogen effluvium
Phase affected Growing hairs Hairs pushed into rest
Timing Days to a few weeks Around three months later
How the hair comes out Breaks; no club root Sheds with a club-shaped root
Extent Can be near-total Diffuse thinning

The root tells the two apart. A hair shed at the end of telogen carries a small white club at its base. A hair lost in anagen effluvium has no such club — it is a broken shaft. That single detail, visible on a hair held up to the light, separates a slow diffuse shed from an acute one.

Because the follicle is stunned rather than destroyed, it usually recovers. Regrowth follows once the cause is removed, though the returning hair can differ in texture or colour for a period.

The most common causes are systemic and identifiable — chemotherapy and radiotherapy above all, and less often severe toxic exposure. It is not a pattern process and is not treated with surgery.

For pattern loss, which behaves nothing like this, see the Norwood scale. For whether surgery is appropriate at all, see should I get a hair transplant.

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Page last updated: 05.09.2026
Editor Contact: fatih@hairofistanbul.com

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