A nurse is caring for a client who is receiving an oral solution of codeine to suppress a nonproductive cough. Which of the following is the nurse's data collection priority following administration of this medication?

A. Heart rate: While important, it is not as directly impacted by codeine as respiratory rate. B. Respiratory rate: Codeine is an opioid and can cause respiratory depression. Monitoring respiratory rate is the priority. C. Blood pressure: Hypotension may occur but is less urgent than respiratory depression. D. Level of consciousness: Sedation is a possible effect, but respiratory rate takes precedence in monitoring.