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?

A. Pseudoparkinsonism is a side effect of antipsychotic medications, characterized by symptoms such as tremors, rigidity, and bradykinesia. However, it does not typically cause hyperpyrexia (fever), diaphoresis (sweating), or blood pressure changes. It is usually less severe than neuroleptic malignant syndrome (NMS). B. Tardive dyskinesia is a movement disorder caused by long-term use of antipsychotic medications. It is characterized by involuntary, repetitive movements such as tongue thrusting, lip smacking, and facial grimacing. It does not cause the acute symptoms described, such as hyperpyrexia and changes in blood pressure. C. Neuroleptic malignant syndrome (NMS) is a potentially life-threatening reaction to antipsychotic medications, characterized by symptoms such as hyperpyrexia (fever), diaphoresis, altered mental status, muscle rigidity, and autonomic dysfunction (e.g., changes in blood pressure). This is a medical emergency, and the client needs immediate intervention. D. Acute dystonia involves sudden, severe muscle spasms, particularly in the neck, face, or back. While it is an adverse effect of antipsychotic medications, it does not typically cause hyperpyrexia or the severe autonomic dysfunction seen in NMS.