Fever-reducing antipyretics typically produce which physiologic response?

• A. Vasodilation and sweating
• B. Vasoconstriction and shivering
• C. Decreased heart rate and sweating
• D. Increased metabolic rate

Answer: (A)

Antipyretics lower fever by lowering the hypothalamic set point back toward normal. When the set point drops, the body responds as if it is overheated and needs to lose heat. The primary heat-loss mechanisms are vasodilation of peripheral blood vessels, which increases blood flow to the skin, and sweating, which promotes evaporative cooling. Together, these processes dissipate heat and bring body temperature down.

Vasoconstriction and shivering would be the body's responses to a higher set point or to keep heat in when fever starts, not the effect of fever reduction. Increased metabolic rate is associated with fever, while decreasing fever typically reduces metabolic demand.