Introduction: The efficiency of psychiatric therapy depends on various factors and drug metabolism is one of them. The liver plays a significant role in drug metabolism through the P450 enzyme systems. However, pharmacogenetics aims to assist clinicians in determining the effectiveness of a particular drug and minimizing potential side effects.

Case report: Here, we present a case to demonstrate the potential use of pharmacogenetics in clinical practice. A 33-year-old male patient with a diagnosis of schizophrenia and OCD had symptoms of sexual auditory hallucinations and obsessive images. According to the patient’s pharmacogenetic profile (CYP2D6, CYP2C9, CYP2C19, CYP1A2 and CYP3A4), the medication started by giving Risperidone 8 mg/day and Aripiprazole 5 mg/day. Aripiprazole was continued at 10 mg/day and then 20 mg/day in the presence of clinical findings. Olanzapine 10 mg/day and Sertraline 50 mg/day were given. In addition, 20 sessions of TMS and 20 sessions of tDCS, which are neuromodulation treatments, were applied.

Results: The patient in question experienced some improvement and partial remission following a treatment plan based on pharmacogenetic analysis. In summary, pharmacogenetic testing can be a valuable tool in determining an appropriate treatment plan that maximizes clinical improvement while minimizing potential adverse effects associated with medication.