Fatal reactions w/ MAOI, pimozide. Mania, HTN or serotonin syndrome w/ selegiline. SSRIs, amphetamine, buspirone, meperidine, nefazodone, serotonin agonists, sibutramine, symphatomimetics, ritonavir, tramadol, venlafaxine may increase risk of serotonin syndrome. May increase effects of benzodiazepines, carbamazepine, carvedilol, clozapine, cyclosporine, dextromethorphan, digoxin, haloperidol, HMG-CoA reductase inhibitors, phenytoin, propafenone, trazodone, TCA, valproic acid & phenothiazines. May increase nephrotoxicity w/ lithium. May increase risk of hyponatremia w/ loop diuretics. May increase hypoprothrombinemic response to warfarin. May decrease effect of tolbutamide.