Methylene blue
Methylene blue is a monoamine oxidase inhibitor (MAOI), and if infused intravenously at doses exceeding 5 mg/kg, may precipitate serious serotonin toxicity, serotonin syndrome, if combined with any selective serotonin reuptake inhibitors (SSRIs) or other serotonin reuptake inhibitor (e.g., duloxetine, sibutramine, venlafaxine, clomipramine, imipramine).