Why Henry III of Navarre's Hair Probably did not Turn White Overnight

Although a rare event, sudden whitening of hair (canities subita) has reportedly affected a number of well-known historical figures, usually in relation to dramatic events in their lives. Although early accounts are substantiated by more recent case reports in scientific literature, we suspect that the phenomenon is not only used as a literary means in fiction, with the aim of dramatizing, but probably also in historical accounts. For this purpose, we examine the case history of Henry III of Navarre who allegedly turned white on the evening of the Saint Bartholomew's day massacre, and challenge this claim, due to inconsistencies in his biography, with the current pathophysiological understanding of canities subita.