Acute Versus Chronic Telogen Hair Loss: A Review of the Knowledge and Recent Facts

Telogen effluvium (TE) is a non-scarring diffuse scalp hair loss condition, with hair shedding ranging from 150 to over 400 hairs per day, particularly concerning for women. The review discusses the mechanisms, causes, clinical types, diagnostic tools, and treatments for TE. Acute TE can often be resolved by addressing the causative factors, while chronic TE presents a more challenging treatment scenario. Diagnostic methods include the hair pull test, clip test, trichoscopy, and modified wash test. New causes of TE include post-hair transplantation, vitamin D deficiency, and COVID-19. Treatment options for chronic TE remain limited and vary in effectiveness.