IMPORTANCE OF THE FIELD: As with all potent therapeutic agents, the use of diuretic compounds has been linked with several adverse effects that may reduce quality of life and patient compliance and, in some cases, may be associated with considerable morbidity and mortality. Among the various types of adverse effects, disturbances of electrolyte and acid-base balance are perhaps the most common, and some of them are the aetiological factors of other side effects (i.e., hypokalaemia causing ventricular arrhythmias or glucose intolerance). The mechanism and site of action and, therefore, the pharmacological effects of each diuretic class largely determine the specific electrolyte or acid-base abnormalities that will accompany the use of each diuretic agent.AREAS COVERED IN THE REVIEW: This article reviews the major electrolyte disturbances (hypokalaemia, hyperkalaemia, hyponatraemia, disorders of magnesium and calcium balance), as well as the acid-base abnormalities complicating the use of the various diuretic agents.WHAT THE READER WILL GAIN: The reader will gain insights into the pathogenesis of the diuretic-induced electrolyte and acid-base disorders together with considerations for their prevention and treatment.TAKE HOME MESSAGE: Knowledge of the pharmacologic properties of each diuretic class and appropriate monitoring of patients under diuretic treatment represent the most important strategies to prevent the development of diuretic-related adverse events and their consequences.