Characteristics of hair loss after COVID-19: A systematic scoping review

Objective While there are literature reporting increased incidence of hair loss in COVID-19 patients, insufficient evidence exists on the topic to date. This review aims to identify the existing evidence and clinical characteristics of hair loss with COVID-19 infection. Methods Following the PRISMA Extension for Scoping Reviews, MEDLINE and EMBASE were searched for all peer-reviewed articles with relevant keywords including "Alopecia," "Telogen Effluvium (TE)," and "COVID-19" from their inception to November 20, 2021. Results A total of 26 articles, with 9 observational studies and 17 case reports or series (a total of 58 cases), were included. Most studies dealt with TE. There were no clear trends between COVID-19 severity and the extent of hair loss. Analysis of the 58 cases also found similar results with most of the cases being female (82.8%), the median onset of hair loss of 2.0 months, and the median time to recovery of hair loss of 5.0 months with a resolution rate of 95%. Conclusion While this systematic review revealed uncertainty and a lack of strong evidence regarding the association of COVID-19 and hair loss, hair loss in COVID-19 may mainly include TE and be reversible in nature. Future studies are warranted to determine the detailed pathophysiology and risk factors of hair loss in COVID-19, including possible roles of estrogen, progesterone, and pro-inflammatory cytokines.