During an infusion of monoclonal antibodies for non-Hodgkin's lymphoma, the patient shows signs of an anaphylactic reaction. What is the nurse's first action?

In the context of an anaphylactic reaction occurring during an infusion of monoclonal antibodies, the first action the nurse should take is to stop the infusion. This immediate step is crucial because continuing the infusion can exacerbate the patient's condition and lead to further complications. By stopping the infusion, the nurse can prevent additional exposure to the allergen and reduce the severity of the reaction.

Once the infusion is stopped, other vital interventions can follow, such as calling for emergency assistance, administering antihistamines, and closely monitoring vital signs. However, the priority is to halt the infusion to mitigate harm and provide a safe environment for subsequent medical interventions. This sequence of actions aligns with established protocols for managing anaphylaxis, where swift cessation of the trigger (in this case, the infusion) is critical to patient safety.