A nurse is monitoring a client who is receiving morphine IV and amitriptyline PO. Which of the following findings indicates an adverse interaction between the prescribed medications?

A. Urinary retention can occur as an adverse effect of both morphine (opioid) and amitriptyline (anticholinergic), which can lead to difficulty urinating. B. Diarrhea is not a common interaction between morphine and amitriptyline. In fact, morphine often causes constipation. C. Low-grade fever is not a known adverse interaction between these two drugs. D. Tachypnea is not a typical adverse effect of the combination of morphine and amitriptyline.