Background: In some medical cases, psychotic symptoms can be part of the clinical picture, and sometimes it can even be the only clinical appearance of the medical condition. Psychotic disorders secondary to organic pathologies affecting the central nervous system are called psychotic disorders due to a general medical condition. While some of these secondary causes can easily be detected by laboratory and imaging methods, anamnesis or neurological examination (substance use, trauma, and tumors), others are often overlooked in the presence of rare medical conditions (autoimmune disease and viral encephalitis), when laboratory and examination findings are not clear and psychiatric symptoms are in the foreground. Case Presentation: In this case, we tried to reveal the differential diagnosis and treatment processes of a patient who was admitted to the emergency department with psychotic symptoms, such as agitation, aggression, and paranoid delusions, and was admitted to the psychiatry clinic after an urgent medical evaluation. After his admission to the psychiatry clinic, the medical evaluation of the patient was re-evaluated in detail due to memory and orientation deterioration, and as a result, clinical pictures such as Hashimoto’s encephalopathy, herpes encephalitis, and epileptic seizures were found to be together in the patient. As a matter of fact, both general medical and psychiatric statuses of the patient improved with the application of low doses and short term antipsychotic treatment for psychiatric symptoms together with the treatment for this underlying general medical condition. Conclusion: Since the treatment of psychiatric symptoms caused by secondary medical factors is quite different from the treatment of primary psychiatric disorders, it is important to make full medical evaluations, especially in patients presenting with psychiatric symptoms for the first time or presenting with emergency psychiatric symptoms.

Keywords: Hashimoto’s encephalopathy, herpes encephalitis, psychotic symptoms, seizure