During a slow IV infusion of a radiopharmaceutical, a middle-aged patient develops flushing, hives, and itching about halfway through the dose. The IV line is patent and must stay usable for emergency medication, and unit policy requires the physician to be told at once. Which immediate action correctly manages this acute reaction?

The correct action is to stop administration of the radiopharmaceutical, preserve the patent IV line with normal saline so emergency medication can be given through it, and notify the physician at once as unit policy requires. Reducing the infusion to a minimal rate may be considered in some contexts for a mild, nonprogressive infusion-related symptom, but it still allows the suspected trigger to enter the patient; with flushing, hives, and itching during administration, the stated requirement is to stop the injection. Stopping and maintaining saline access while assessing the patient before calling may be a familiar sequence when an initial assessment is needed, but it delays physician notification and conflicts with the explicit requirement to report immediately. Promptly notifying the charge nurse is a useful escalation step in many units, but it does not satisfy the stated requirement to tell the physician at once; a nurse notification should not substitute for that call. Exam caveat: follow local reaction protocols for assessment and emergency treatment, but do not let those steps delay a required immediate physician notification. Practical check: verify that the radiopharmaceutical is no longer infusing, the IV remains patent with saline, and the physician has received the notification.