Telogen Effluvium
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.
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.
Related terms
For diffuse thinning that is not sudden, see seeing scalp through your hair. For pattern loss instead, see the Norwood scale.
Articles on specific suspected triggers: statins and hair loss, melatonin and hair loss and hair loss in syphilis.
