a rare type of septicemia (blood poisoning) of rapid and severe onset, marked by fever, collapse and sometimes coma, hemorrhage from skin and mucous membranes, and severe bilateral hemorrhage of the adrenal cortical tissue. The syndrome is most common in children under five and may last only a few hours; resulting adrenal apoplexy is the immediate cause of death.

Treatment, which must be immediate, is by large doses of antibiotics to combat the septicemia and of adrenal hormones, especially glucocorticoids. Though the meningococci (meningococcus) of cerebrospinal fever are the typical pathogens involved, other organisms, such as streptococci and pneumococci, may be involved. The syndrome is named after the British physician Rupert Waterhouse and the Danish physician Carl Friderichsen, who independently described it in the early 1900s.