Fluphenazine decanoate is primarily used in the treatment of chronic psychotic disorders, such as schizophrenia. It is administered as a long-acting injectable formulation, which helps in maintaining consistent therapeutic levels of the medication in the body, reducing the frequency of dosing. This is particularly beneficial for patients who have difficulty adhering to daily oral medication regimens. The drug works by blocking dopamine receptors in the brain, which helps to alleviate symptoms like hallucinations, delusions, and disorganized thinking. Its long-acting nature makes it a valuable option for managing symptoms over extended periods, thereby improving the quality of life for individuals with severe mental health conditions. Regular monitoring is essential to manage potential side effects, which can include extrapyramidal symptoms and sedation.