While hypovolemic shock from dehydration is appropriately treated with IV fluids, giving crystalloid to patients with hypovolemic shock from hemorrhage can be absolutely detrimental. An important trial from 1993 showed that pre-hospital fluids administered to hypotensive patients with penetrating thoracic trauma increased mortality compared to no fluids given, with the group receiving fluids getting just 800 milliliters more than the control on average.⁵ This finding has since been confirmed in numerous studies, and the standard practice to limit crystalloid in favor of early administration of blood in hypotensive trauma patients.6 Diluting the little blood hemorrhaging patients have with salt water only worsens their ability to deliver oxygen to tissue and clot off the source of bleeding. 

Sepsis is the 10th leading cause of death, and fluid administration has long been a cornerstone of the management of septic patients. The landmark 2001 study by Emanuel Rivers on early goal directed therapy (EGDT) featured fluid resuscitation as a central feature of a bundle of interventions, and patients in the EGDT group received on average almost five liters of fluids in the first six hours of treatment.7 EGDT has since been “debunked” (although I think it is important to recognize the attention that the Rivers’s original trial brought toward improving the quality of sepsis care) in several studies.^8-10 What’s more, fluid overload has consistently been associated with increased mortality in critically ill patients with sepsis.^11-12 In light of these revelations, the Surviving Sepsis Campaign in 2021 changed its recommendation to give 30 ml/kg of fluids to sepsis patients with hypo-perfusion to a suggestion, acknowledging that the evidence for doing so is of low quality.¹³

Emerging literature shows benefit from starting vasopressors early in septic shock.^14-15 This makes physiologic sense. Septic shock is a form of distributive shock, not hypovolemic. No amount of fluid will resolve it without first clamping down the leaky blood vessels that result from the systemic inflammatory response triggered by the underlying infection.

Perhaps the most provocative evidence that calls into question the utility of IV fluids is found in the FEAST trial. Published in 2011 in the New England Journal of Medicine, the study compared a 20–40 mL/kg fluid bolus to no bolus in the treatment of critically ill children with signs of impaired perfusion in resource-limited settings in sub-Saharan Africa.¹⁶ Each group received antibiotics, maintenance IV fluids, and supportive care as needed. The primary outcome was mortality at 48 hours.