Severe infections are a common cause of hospitalisation and outcomes for Māori are worse. These infections are treated with large volume fluids through a vein (IV fluid) and medicine to increase blood pressure (vasopressors) if fluids fail. Recent evidence suggests large volume fluids may be harmful. This study will investigate if giving smaller volumes of IV fluid and vasopressors leads to better patient outcomes than giving a larger amount of fluid before starting vasopressors. Patients eligible for the trial will be randomly allocated to receive one of these treatment regimens. The main outcome we will measure is the number of days the patient has survived out of hospital at 90 days. This patient-centred measure was chosen in consultation with consumers and captures survival, illness severity and quality of life. The trial will recruit 1160 patients from emergency departments in hospitals throughout Australia and Aotearoa/New Zealand.