What condition can develop within 5 days of starting haloperidol?

Haloperidol is an antipsychotic medication primarily used to treat schizophrenia and other psychotic disorders. One of the notable side effects of haloperidol, particularly when used at higher doses or for prolonged periods, is the development of extrapyramidal symptoms—one of which is Parkinsonism.

Parkinsonism can occur within a relatively short time frame after starting treatment with haloperidol, often manifesting within the first five days. This condition includes symptoms such as tremors, rigidity, bradykinesia, and postural instability, resembling the symptoms of Parkinson’s disease, due to the drug's antagonistic action on dopamine receptors in the brain.

In contrast, other conditions listed, such as cognitive deficits, anxiety disorder, and psychosis, do not typically emerge as rapidly after initiating haloperidol therapy. Cognitive deficits might develop over a longer duration with chronic use, anxiety disorder is not a direct consequence of haloperidol, and while the drug is used to manage psychosis, the onset of psychotic symptoms would not coincide with starting the medication in a patient who is being treated for an existing psychotic condition. Thus, the correct answer highlights a well-documented and time-sensitive side effect of haloperidol.