Practical Prescribing is a series created in collaboration with the Drug and Therapeutics Bulletin that alerts prescribers to important issues and promotes shared decision-making with patients and caregivers. The series is intended for all medical and non-medical prescribers, especially doctors in training, and focuses on commonly prescribed drugs in primary and secondary care. The advisers are Fraz Mir of Addenbrooke's Hospital, Cambridge, and David Phizackerley, former deputy editor of the Drug and Therapeutics Bulletin. Potassium-sparing diuretics are effective in the treatment of mild hypervolemia or to enhance the effect of other diuretics. Potassium levels and renal function should be monitored due to the risk of hyperkalemia. Aldosterone-blocking potassium-sparing diuretics such as spironolactone, eplerenone, and finerenone improve outcomes in heart failure patients with reduced ejection fraction and with preserved ejection fraction.