Final answer:
The nurse should caution the client about taking benzodiazepines while receiving an opioid analgesic.
Step-by-step explanation:
The nurse should caution the client about taking benzodiazepines while receiving an opioid analgesic. Benzodiazepines are central nervous system depressants that can increase the sedative effects of opioids, leading to respiratory depression and increased risk of overdose. Examples of benzodiazepines include Xanax, Valium, and Ativan.