A nurse is caring for a client who has been prescribed prochlorperazine (Compazine) for postoperative nausea. Which of the following reported signs can indicate a potential complication of this medication?

A. Nausea is the symptom prochlorperazine is intended to treat, so its occurrence would suggest that the medication is not effective rather than being a complication. B. Prolonged QT interval is not a typical complication of prochlorperazine; it is more commonly associated with medications like ondansetron. C. Restlessness can indicate akathisia, a potential extrapyramidal side effect of prochlorperazine. This condition involves an intense feeling of restlessness and the need to move, commonly associated with dopamine antagonists. D. Vomiting is a symptom treated by prochlorperazine and would likely occur due to inadequate control rather than being a complication of the drug itself.