Endotoxin – a pyrogenic product (e.g. lipopolysaccharide) present in the bacterial cell wall.

Endotoxin – a heat-stable toxin associated with the outer membranes of certain gram-negative bacteria, including Brucella, Neisseria, and Vibrio species. Endotoxins are not secreted but are released only when the cells are disrupted; they are less potent and less specific than the exotoxins, and they do not form toxoids. In large quantities they produce hemorrhagic shock and severe diarrhea; smaller amounts cause fever, altered resistance to bacterial infection, leukopenia followed by leukocytosis, and numerous other biologic effects.
Endotoxin can lead to reactions in patients receiving injections ranging from fever to death.