What should the nurse do when a patient exhibits signs of an allergic reaction while on penicillin?

When a patient exhibits signs of an allergic reaction while taking penicillin, the appropriate action for the nurse is to hold the next dose and notify the prescriber. This is essential for patient safety; administering the medication again could exacerbate the allergic reaction and potentially lead to more severe complications, such as anaphylaxis.

Holding the dose allows time for the healthcare provider to assess the situation and consider alternative treatment options or interventions. Notifying the prescriber is crucial because they need to be aware of the patient's adverse reaction to make informed decisions regarding the patient's medication plan and overall treatment.

Other options, such as requesting a chest radiograph, would not directly address the immediate concern of allergic reaction management and might delay necessary interventions. Administering the next dose without addressing the allergic signs could put the patient at risk. While antihistamines can be part of a treatment plan for allergic reactions, determining the appropriateness and timing of their administration would typically fall under the prescriber's purview in this scenario. Therefore, the most prudent nursing action is to hold the medication and inform the prescriber.