A patient is receiving an infusion of morphine sulfate for pain relief, but their pain is not completely controlled. The addition of diazepam has been ordered for this patient. The nurse questions this order because which severe side effect of opioids is more likely to occur if taken with diazepam?

A. respiratory depression: Both morphine, an opioid agonist, and diazepam, a benzodiazepine, depress the central nervous system by enhancing inhibitory neurotransmission. When combined, their synergistic effects increase the risk of profound respiratory depression, hypoventilation, and hypoxia. This is a life-threatening interaction and a key reason the nurse should question the order. B. gastrointestinal bleeding: Opioids like morphine can cause constipation, but they are not associated with GI bleeding. Diazepam does not contribute to gastrointestinal hemorrhage, so this is not a primary concern with their combination. C. pulmonary fibrosis: Pulmonary fibrosis is a chronic interstitial lung disease typically associated with drugs like amiodarone or certain chemotherapeutics, not opioids or benzodiazepines. It is not a relevant risk in this scenario. D. constipation: Morphine can reduce gastrointestinal motility, leading to constipation, but this is a common and manageable side effect. Diazepam does not significantly worsen constipation, and it is not considered a severe or emergent side effect of the combination.