Antipyretics are drugs that prevent or reduce fever by lowering the body temperature from a raised state. However, they will not affect the normal body temperature if one does not have fever.
Antipyretics cause the hypothalamus to override an interleukin-induced increase in temperature. The body will then work to lower the temperature and the result is a reduction in fever.
Most are also used for other purposes. For example, the most common antipyretics in the United States are aspirin and acetaminophen, which are used primarily as pain relievers. There is some debate over the appropriate use of such medications: fever is part of the body's immune response to infection.