BACKGROUND Sepsis is associated with impaired tissue perfusion and elevated serum lactate, a key prognostic marker. Magnesium plays a vital role in cellular energy metabolism and may enhance lactate clearance in sepsis. AIM To investigate the impact of magnesium on the clearance of lactate in critically sick patients with sepsis. METHODS In this triple-blind, randomized trial, 138 adult patients with a diagnosis of sepsis (according to Sepsis-3 guidelines) and with serum lactate levels > 2 mm