Which of the following is a sign of a systemic reaction to IV therapy?

A fever is a common sign of a systemic reaction to IV therapy. When a patient experiences a systemic reaction, it typically indicates a response throughout the body rather than localized to the site of the IV insertion. This can occur due to various reasons such as an allergic reaction to the infused fluid, an infection, or a febrile non-hemolytic reaction from the components in the IV solution. The presence of fever is significant as it reflects an elevation in the body's temperature set point, often in response to an immune reaction, signaling that something is not right.

In contrast, local redness, swelling at the site, and nausea do not indicate a systemic reaction. Local redness and swelling at the IV site suggest a localized response, possibly due to infiltration, phlebitis, or infection at the insertion site. Nausea, while uncomfortable and potentially related to various factors, does not specifically signify a systemic reaction in the context of IV therapy. It can stem from numerous causes, including adverse reactions to medications infused but not necessarily indicating a systemic response akin to a fever. Thus, fever serves as the key indicator of a systemic issue arising from IV therapy.