Risk of serotonin syndrome w/ non-selective as well as selective A (moclobemide) & B (selegiline) MAOIs. May potentiate CV effects of adrenaline, ephedrine, isoprenaline, noradrenaline, phenylephrine & phenylpropanolamine (eg, as contained in local & general anaesth & nasal decongestants). May counteract antihypertensive effects of guanethidine, betanidine, reserpine, clonidine & methyldopa. Increased risk of paralytic ileus, hyperpyrexia w/ anticholinergic agents. May increase QT interval w/ class Ia & III antiarrhythmics (eg, quinidine, amiodarone, sotalol, dofetilide), antipsychotics (eg, thioridazine), macrolides (eg, erythromycin), antihistamine (eg, terfenadine, astemizole), quinolone antibiotics (eg, gatifloxacin, moxifloxacin), cisapride, lithium. Increase QT prolongation & malignant arrhythmias w/ thiazide diuretics. May enhance effects of alcohol, barbiturates & other CNS depressants. Increased neurotoxicity w/ lithium. May reduce the effect of levodopa & increase risk of cardiac side effects.