Telogen effluvium is a temporary form of diffuse hair shedding that occurs when a stressor pushes a large number of follicles into the resting phase at once. Common triggers include significant illness, surgery, childbirth, rapid weight loss, iron deficiency and emotional stress.
Shedding typically appears two to three months after the trigger and settles once the cause resolves, with regrowth over several months. A doctor can help identify the trigger, order blood tests and rule out pattern hair loss, which needs different management.