COVID-19 induced telogen effluvium.

COVID-19 is a febrile, infectious illness that has previously been associated with telogen effluvium (TE). However, to date, no study has been conducted to determine the incidence of TE in those who have had COVID-19. To assess the frequency of TE in post-COVID-19 patients and the correlation between the development of TE and the severity of COVID-19, to understand whether emotional stress or medications are responsible for the development of TE. Totally 204 patients with a history of SARS-CoV-2 infection in the last 3 months were included in the study. The diagnosis of TE was made by history of excessive hair shedding, hair pull test, diffuse or bitemporal thinning, and absence of anisotrichosis in trichoscopy. Patients who did not have any TE cause other than COVID-19 and whose hair loss started after COVID-19 were considered as "COVID-19 associated TE (CATE)." We found TE in 75 (36.7%) cases and androgenetic alopecia (AGA) in 85 (41.7%) cases. CATE was present in 27.9% of cases and developed on average 53.76 (± 23.772) days after COVID-19 real-time reverse transcription polymerase chain reaction (RT-PCR) positivity. The proportion of patients with CATE was numerically higher in hospitalized patients compared to outpatients (31.7% vs. 24.3%; p = 0.238); and significantly higher in women compared to men (42.3% vs. 6.2%; p < 0.001), in patients with hypertension compared to those without hypertension (40.4% vs. 23.1%; p = 0.014), and in patients who had respiratory symptoms compared to those who had not (31.7% vs. 14.0%; p = 0.021). The patients with and without CATE were similar in terms of stress level and usage of COVID-19 medications. Patients with AGA had a higher rate of hospitalization (69.4% vs. 35.3%; p < 0.001) and a higher incidence of fever (69.4% vs. 54.6%; p = 0.033) during COVID-19, compared to those without. TE developed in approximately one-quarter of people who have had COVID-19, and our study is the first to detect it. The time to onset of CATE, which was 7-8 weeks after the SARS-CoV-2 RT-PCR positivity, was not much different from post-infectious TE. Patients with severe COVID-19 seem to be more prone to develop TE. The presence of AGA is associated with a more severe COVID-19. During the pandemic, clinicians should consider a previous SARS-CoV-2 infection in patients presenting with hair loss.