BACKGROUND Intravenous fluids (IVF) are frequently utilized to restore intravascular volume in patients with distributive and hypovolemic shock. Although the benefits of the appropriate use of fluids in intensive care units (ICUs) and hospitals are well described, there is growing knowledge regarding the potential risks of volume overload and its impact on organ failure and mortality. To avoid volume overload and its associated complications, strategies to identify fluid responsiveness are developed and utilized more often among ICU patients. Apart from the amount of fluid utilized for resuscitation, the type of fluid used also impacts patient outcome. Colloids and crystalloids are two types of fluids that are utilized for resuscitation. The efficacy of each fluid type on the expansion of intravascular volume on one hand and the potential adverse effects of each individual fluid, on the other hand, need to be considered when choosing the type of fluid for resuscitation. The negative impact of hydroxyethyl starch on kidney function, of albumin on the mortality of head trauma patients and chloride-rich crystalloids on mortality and kidney function, are only examples of new developments in the field. SUMMARY In this paper, we will review the impact of fluid overload on patient outcomes, define the fluid challenge, describe the differences in static and dynamic estimates of fluid responsiveness, and review the effect of different types of fluid on patient outcome. KEY MESSAGE Avoiding fluid overload by choosing the appropriate amount of fluids in patients who are fluid-responsive on one hand, and treating IVF like other medications, on the other hand, are the major changes. Whenever clinicians decide to prescribe IVF, they need to weigh the risks and benefits of giving fluid and also the advantages and side effects of each fluid type in order to optimize patient outcomes.