A nurse is caring for a client who has major depression and a new prescription for citalopram. Which of the following adverse effects is the priority for the nurse to report to the provider?

Citalopram is a selective serotonin reuptake inhibitor (SSRI) used to manage major depressive disorder by increasing serotonin levels in the synaptic cleft. While generally well-tolerated, SSRIs can cause serotonin syndrome, a potentially fatal condition characterized by altered mental status, autonomic instability, and neuromuscular hyperactivity. Early detection of neurological changes is vital. Rationale: A. Bruxism, or involuntary teeth grinding, is a known side effect of SSRIs that typically occurs during sleep. While it can cause dental wear and jaw pain, it is not a life-threatening emergency requiring immediate reporting. The nurse can suggest a mouth guard or a dosage adjustment during a routine follow-up with the provider to manage this specific discomfort. B. Insomnia is a frequent side effect of citalopram due to the stimulating effects of increased serotonin in certain brain pathways. While significant for the client's quality of life, it is an expected reaction that often subsides after several weeks of therapy. It does not carry the same degree of clinical urgency as symptoms indicating acute toxicity or systemic physiological distress. C. Weight loss can occur during the initial phase of citalopram therapy due to decreased appetite or nausea. While the nurse should monitor the client's nutritional intake and weight over time, it is a gradual process rather than an acute crisis. It is considered a manageable side effect that rarely requires immediate medical intervention unless the weight loss becomes extreme. D. Confusion is a priority finding because it may indicate the onset of serotonin syndrome or significant hyponatremia, which are serious complications of SSRI therapy. Altered mental status is a "red flag" symptom that suggests systemic toxicity rather than a benign side effect. The nurse must report confusion immediately to ensure the client is evaluated for potentially life-threatening drug reactions.