This article was first published on October 5, 2022 It was last edited or updated on October 5, 2022. Methadone has been associated with clinically-significant prolongation of the QTc interval (Perrin-Terrin et al., 2011; Pearson and Woosley, 2005). How serious can this methadone-induced QTc prolongation be? Many cases of torsades de pointes attributed to methadone…