Unexpected Extensive Hair Whitening Following Baricitinib Treatment for Alopecia Universalis: A Case Report and Mechanistic Insights

A case report details a young male with alopecia universalis who experienced significant hair regrowth but also extensive hair whitening after treatment with baricitinib, a JAK inhibitor. Initially, both black and white hairs appeared, but by the second month, most hair turned white, and this depigmentation persisted over seven months without repigmentation. Despite the whitening, baricitinib was well tolerated with no significant adverse effects. The report suggests that baricitinib's modulation of the JAK-STAT pathway may affect melanocyte function and hair pigmentation, indicating a need for further research to understand this unexpected side effect and to develop therapies addressing both hair regrowth and pigmentation in alopecia areata.