Emergency fluid resuscitation of hypovolemic patients begins with an accurate assessment of the degree of volume depletion as well as identification of the cause and associated abnormalities. On the basis of this information, the proper resuscitative fluid can be chosen and administered by the appropriate route, as guided by the urgency of the situation. Patients with severe volume depletion and those in shock require intravenous fluids. In other situations, oral rehydration is often appropriate. Specific fluids then can be tailored to the individual patient's needs and adjusted as warranted by ongoing monitoring.