A nurse is preparing to administer an opioid agonist to a client who has acute pain. For which of the following manifestations should the nurse monitor as an adverse effect of this medication?

The correct answer is D: Urinary retention. Opioid agonists can cause urinary retention by affecting the smooth muscle tone of the bladder and urethra. The nurse should monitor for this adverse effect by assessing the client's ability to urinate and monitoring for signs of urinary retention such as discomfort, distended bladder, or decreased urine output. Choices A, B, and C are incorrect because irritating cough, tachypnea, and hypertension are not typically associated with opioid agonist use.