tokens: 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 ) .