The present disclosure relates to methods of transitioning patients or obese patients being treated with vortioxetine to treatment with a monoamine oxidase inhibitor (MAOI). The methods provided include delaying administration of the MAOI for certain time periods after stopping administration of vortioxetine. The patients or obese patients possess various capabilities of metabolizing vortioxetine. The current disclosure also includes methods of switching patients to a MAOI intended to treat psychiatric disorders while being treated with vortioxetine. The methods disclosed further comprise determining vortioxetine plasma clearance and washout time for patients with different body fat status and/or different CYP2D6 metabolizer status.
