Final answer:
An elevated body temperature should be reported as it is a symptom of neuroleptic malignant syndrome (NMS), a potentially fatal side effect of antipsychotic medications like haloperidol.
Step-by-step explanation:
The nurse should report an elevated body temperature to the provider as a manifestation of neuroleptic malignant syndrome (NMS). NMS is a life-threatening condition often caused by antipsychotic medications, such as haloperidol. It is characterized by a tetrad of symptoms: hyperthermia (elevated body temperature), autonomic instability, altered mental status, and muscle rigidity. Among the options provided, increased appetite, improved concentration, and decreased blood pressure are not typically associated with NMS.
Haloperidol is an antipsychotic medication that affects dopamine activity, primarily in the basal nuclei of the brain, leading to side effects that can resemble movement disorders of the extrapyramidal system. One of the severe side effects of this medication can be the development of NMS, which demands immediate medical attention.