The medical management of marathon casualties involves several potential treatment pathways. It is helpful to develop defined treatment protocols for commonly experienced conditions addressing intervention selection criteria and monitoring response to therapy. Providing intravenous (IV) fluids for runners post marathon should be scrutinised based upon the effectiveness and safety of the intervention. Commonly agreed upon indications for IV fluids are replacement for clinical dehydration and support for unconscious, hypoglycaemic or persistently hypotensive athletes. Most clinicians recommend serum sodium evaluation prior to IV initiation. IV fluid use in athletes with persistent nausea, generalised muscle cramping and to augment whole-body cooling is commonly deployed despite the paucity of supporting scientific evidence and remains an area for further study. Marathon medical support leaders should develop and disseminate guidelines to direct the administration of IV fluids at their medical aid stations.