I've merged your threads as they are on the same topic. It's just to keep the forum tidy-ish.
I can't take duloxetine as it makes me ill but I know that Stella takes mirtazapine alongside her duloxetine, and I've had mirtazapine alongside sertraline. There is also an academic study ongoing about the use of mirtazapine in addition to another AD in treatment resistant depression.