The majority of dengue patients may be treated in hospital outpatient departments, with only the most severe cases requiring hospitalization. The World Health Organization, or WHO, has issued a recommendation on the symptoms that should lead to hospitalization in patients. They state that patients should be hospitalized if they have plasma leakage (increased volume of fluid outside the blood vessel, usually due to increased permeability of capillaries) or severe hemorrhage. Hospitalization is also recommended for patients who develop warning signs of plasma leakage or severe bleeding. These include: rapid decrease in platelet count, persistent vomiting, restlessness, easy bruising or bleeding from any site, red eyes caused by low blood pressure, and decreased urine output. Patients do not need to be hospitalized for simple dengue fever. Those who are well enough to be discharged can go home, but will need to stay away from work and school until it's clear they are no longer at risk of developing serious complications. In some cases, patients may require supplemental oxygen, intravenous fluids, and blood products such as transfusions or clotting factors if they experience significant bleeding. Patients with these needs may be given special care in a specialized unit known as an intensive care unit or ICU.