HOI Encyclopedia Category: Hair Loss Disorders

Telogen Effluvium

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

Telogen effluvium is diffuse hair shedding that follows a physiological shock, when a large share of growing follicles is pushed into the resting phase at once and releases its hairs together some weeks later. The follicles remain intact and acute cases are usually self-limiting.

Key Facts

What it is Diffuse shedding after a systemic trigger
Delay Typically about three months, range one to six
Distribution Whole scalp, not a pattern
Follicles Intact, not miniaturizing
Acute vs chronic Chronic persists beyond six months
For surgery A reason to postpone, not to operate

Telogen effluvium is shedding, not balding. A physiological shock pushes a large share of growing follicles into the resting phase at once. They all release their hairs together some weeks later, so the loss is diffuse across the whole scalp rather than following a pattern — and the follicles themselves are unharmed.

The delay is what confuses people. Shedding typically appears about three months after the trigger, with a range of roughly one to six, so the event that caused it is often forgotten by the time hair starts coming out. On a healthy scalp around 15% of hairs are resting at any time; in telogen effluvium a large proportion of growing hairs is precipitated into that phase at once (Hughes, Syed & Saleh, Telogen Effluvium, StatPearls).

Telogen effluvium Pattern hair loss
Distribution Diffuse, whole scalp Follows a pattern
Onset Sudden, weeks after a trigger Gradual, over years
Follicles Intact Progressively miniaturizing
Course Usually self-limiting Progressive without treatment

Acute cases resolve; chronic ones persist past six months. Common triggers include illness, surgery, childbirth, thyroid disease, nutritional deficiency and certain medications. Because the trigger is systemic, the answer is finding it rather than treating the scalp.

It is a reason to postpone surgery, not to schedule it. Operating during active diffuse shedding makes assessment unreliable and the result impossible to judge.

For diffuse thinning that is not sudden, see seeing scalp through your hair. For pattern loss instead, see the Norwood scale.

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

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