How dangerous are diuretics?

The proposal that thiazide diuretics may increase cardiovascular risk receives no support from recent data. Current evidence does not indicate that diuretic-induced hypokalaemia is associated with increased ventricular arrhythmias. This evidence includes continuous electrocardiographic monitoring--which is the most sensitive technique for quantitating cardiac arrhythmias. In contrast to earlier reports, more recent studies found no evidence for increased arrhythmias during the period of hypokalaemia, or for decreased arrhythmic activity after correction of hypokalaemia. Similarly, studies claiming increased sudden death in patients on diuretic treatment have not been substantiated by the results of other large-scale trials. Elevation of serum cholesterol concentrations with thiazide appears to be a short term phenomenon since most studies indicate the elevation reverts to baseline during long term treatment. Thiazide diuretics remain as one of our most effective antihypertensive agents. Fears of their increasing the incidence of ventricular arrhythmias due to hypokalaemia, or constituting a risk factor for atherosclerosis by elevating serum cholesterol concentrations, appear largely unsubstantiated.