A nurse in an emergency department is assessing a client who has been taking haloperidol for 3 months. The client has a temperature of 39.7° C (103.4° F), blood pressure of 150/110 mm Hg, and muscle rigidity. Which of the following complications should the nurse suspect?

Choice A reason: Agranulocytosis is a severe reduction in white blood cells, most commonly associated with clozapine use rather than haloperidol. It presents with signs of infection such as fever and sore throat, but not with muscle rigidity and autonomic instability. Choice B reason: Tardive dyskinesia is a late-onset extrapyramidal side effect characterized by involuntary movements of the face, tongue, and extremities. It does not present with hyperthermia, hypertension, or muscle rigidity, making it inconsistent with the current clinical picture. Choice C reason: Akathisia is a movement disorder marked by inner restlessness and the inability to stay still. While distressing, it does not cause fever, severe hypertension, or muscle rigidity, so it is not the complication described here. Choice D reason: Neuroleptic malignant syndrome is a life-threatening reaction to antipsychotic medications such as haloperidol. It is characterized by hyperthermia, severe muscle rigidity, autonomic instability (including hypertension), and altered mental status. The client’s presentation matches this condition exactly, making it the correct answer.