BACKGROUND: Hyperkalaemia is a life-threatening electrolyte disturbance and also a potential cause of cardiac arrest. The objective was to assess the effects of acute pharmacological interventions for the treatment of hyperkalaemia in patients with and without cardiac arrest. METHODS: The review was reported according to PRISMA guidelines and registered on PROSPERO (CRD42023440553). We searched OVID Medline, EMBASE, and CENTRAL on September 9, 2024 for randomized trials, non-randomized trials, observational studies, and experimental animal studies. Two investigators performed abstract screening, full-text review, data extraction, and bias assessment. Outcomes included potassium levels, ECG findings, and clinical outcomes. Certainty of evidence was evaluated using GRADE. RESULTS: A total of 101 studies were included, with two studies including patients with cardiac arrest. In meta-analyses including adult patients without cardiac arrest, treated with insulin in combination with glucose, inhaled salbutamol, intravenous salbutamol dissolved in glucose, or a combination, the average reduction in potassium was between 0.7 and 1.2 mmol/l (very low to low certainty of evidence). The use of bicarbonate had no effect on potassium levels (very low certainty of evidence). In neonatal and paediatric populations, inhaled salbutamol and intravenous salbutamol reduced the average potassium between 0.9 and 1.0 mmol/l (very low to low certainty of evidence). There was no evidence to support a clinical beneficial effect of calcium for treatment of hyperkalemia. CONCLUSIONS: Evidence supports treatment with insulin in combination with glucose, inhaled or intravenous sal-butamol, or the combination. No evidence supporting a clinical effect of calcium or bicarbonate for hyperkalaemia was identified.