Risk of serotonin syndrome w/ irreversible, non-selective MAOIs, linezolid & methylene blue. Inhibited metabolism of metoprolol, mequitazine. Reduced efficacy of tamoxifen. Changes in blood levels w/ phenytoin. Prolonged QT interval w/ class IA & III antiarrythmics, antipsychotics, TCAs, sparfloxacin, moxifloxacin, erythromycin IV, pentamidine, halofantrine, astemizole, mizolastine. Risk of increased bleeding w/ oral anticoagulant, aspirin & NSAIDs. Reduced antidepressant activity w/ cyproheptadine. Increased risk of hyponatremia w/ diuretics, desmopressin, carbamazepine, oxcarbazepine. Lowered seizure threshold w/ TCAs, other SSRIs, phenothiazines, butyrophenones, mefloquine, chloroquine, bupropion, tramadol. Concomitant use w/ drugs metabolized by CYP2D6 eg, fleicainide, propafenone, nebivolol, atomoxetine, carbamazepine; iproniazid, alcohol, lithium, tramadol, triptans, tryptophan, selegiline, St. John's wort, flecainide, propafenone, nebivolol, atomoxetine, risperidone.