Hyponatraemia is the most common electrolyte disorder seen in clinical practice and the consequences can range from minor symptoms to life-threatening complications including seizures and cardiorespiratory distress. These effects occur as a result of fluid shifts due to deranged serum tonicity and subsequent cerebral oedema. The appropriate assessment and management of patients with hyponatraemia is not always achieved in clinical practice, which is partly related to challenges in teaching with limited clinical guidance. Recently, the European Society of Endocrinology, European Society of Intensive Care Medicine and European Renal Association–European Dialysis and Transplant Association produced clinical practice guidelines to focus on appropriate investigation and management of these patients. Within this manuscript, we highlight the key points from these guidelines, which are most pertinent to doctors of all specialties to improve the care of patients with this common electrolyte disorder.