When bacterial pyrogens are injected in sufficient amounts, perhaps in microgram quantities, the fever produced is accompanied by chills, body aches, a rise in blood pressure, and possibly a state of shock and death.

Are pyrogens bad?

Pyrogens are fever-inducing substances usually derived from microorganisms [endotoxins or lipopolysaccharide (LPS)] and when present systemically in sufficient quantity can lead to severe signs of inflammation, shock, multiorgan failure, and sometimes even death in humans.

How does pyrogen cause fever in the human body?

The pyrogens inhibit heat-sensing neurons and excite cold-sensing ones, and the altering of these temperature sensors deceives the hypothalamus into thinking the body is cooler than it actually is. In response, the hypothalamus raises the body's temperature above the normal range, thereby causing a fever.