A nurse is assessing a client who is receiving treatment with multiple antipsychotic medications and who suddenly became ill. Findings include blood pressure changes, hyperpyrexia, and diaphoresis. The nurse should recognize that which of the following adverse effects may be occurring?

Choice A reason: Pseudoparkinsonism involves tremors, shuffling gait, rigidity, and bradykinesia, but it does not cause high fever, blood pressure instability, or diaphoresis. Choice B reason: Tardive dyskinesia involves involuntary movements such as lip smacking, tongue protrusion, or grimacing, and it develops gradually after long-term medication use. It does not cause acute systemic symptoms. Choice C reason: Neuroleptic malignant syndrome (NMS) is a rare but life-threatening reaction to antipsychotics. It presents with hyperpyrexia, autonomic instability (blood pressure changes, diaphoresis), muscle rigidity, and altered mental status. This fits the scenario. Choice D reason: Acute dystonia is characterized by sudden, severe muscle contractions (often of the neck, eyes, or jaw) but does not include fever or autonomic instability.