Telogen Effluvium

Telogen Effluvium

Telogen effluvium is a reversible form of diffuse hair shedding caused by a physiological or psychological stressor that shifts a larger-than-normal fraction of scalp hair follicles from the active growth phase (anagen) into the resting phase (telogen). Approximately 2-3 months after the stressor, those follicles release their hairs, producing visibly increased shedding. The condition is self-limited; affected follicles re-enter the growth phase and hair density typically recovers within 6-12 months once the underlying stressor has resolved.

Common triggers include rapid or substantial weight loss, severe illness, surgery, childbirth, major emotional stress, abrupt discontinuation of estrogen-containing medications, and certain micronutrient deficiencies (notably iron, zinc, and vitamin D). The diagnosis is clinical, supported by a positive hair pull test in which more than 10% of pulled hairs come away in telogen phase.

In the context of obesity pharmacotherapy, telogen effluvium has been reported with all the GLP-1-class agents — semaglutide, tirzepatide, and is likely to be reported with retatrutide once Phase 3 long-term safety data are fully characterized. The mechanism is most likely the rapid weight loss itself rather than a direct drug effect on hair follicles, mirroring the same pattern seen after bariatric surgery and very-low-calorie diet interventions.

Clinical management is primarily reassurance and time. Maintaining adequate dietary protein (typically 1.2-1.6 g/kg of ideal body weight per day), supplementing iron and vitamin D if levels are low, and avoiding aggressive caloric restriction beyond what the medication produces can support recovery. Topical minoxidil is sometimes used but its effect in this specific setting is limited. Hair density typically returns to baseline within several months of weight stabilization.