Acute symptomatic hyponatraemia results in potentially fatal cerebral oedema, whereas overly rapid correction of hyponatraemia can cause osmotic demyelination syndrome (ODS) with permanent neurological damage. To balance these two risks, we recommend a limited rapid increase of serum sodium level by at least 5 mmol/l by administration of fixed bolus(es) of hypertonic saline (HTS) to reverse symptoms of cerebral oedema, while limiting total increase to 8–10 mmol/l in the first 24 h, and each subsequent 24 h period. Neurological status, urine output, and biochemistry should be carefully monitored. Desmopressin and/or intravenous dextrose are recommended to reverse or prevent overly rapid correction. Interventional trials focused on optimal HTS volume, best approaches for prevention and treatment of overly rapid correction, and their clinical outcomes are needed for strong evidence-based recommendations.