Increased toxicity w/ sympathomimetic agents (eg, epinephrine) & general anesth (eg, halothane). Hypertensive crisis w/ medicines for depression (eg, amitriptyline, imipramine, sertraline, moclobemide). Phenylephrine: Decreased effect w/ adrenergic blocking agent (eg, phenothiazine drugs, phentolamine, propranolol). Paracetamol: May increase susceptibility to the harmful effects to the liver w/ medicines for convulsion (eg, phenobarb). Increased risk of bleeding w/ warfarin. Increased anticoagulation effect of warfarin.