Objectives: The aim of this study was to determine the incidence of psychoactive substance usage in patients diagnosed and treated with first episode psychosis. We also researched if there are any differences in using different therapy approaches considering the cause of psychotic episode. Study design: cross-sectional study with historical data Participants and methods: The total of 100 patients who were admitted and treated with first episode psychosis between January 2018 and December 2019 participated in this cross-sectional study. Participants were separated into two groups, given the cause of their first episode psychosis. Patients who consumed psychoactive substances were placed in the first group, and patients who did not consume psychoactive substances into the second. Demographic and clinical characteristics were taken from the medical records. Results: Out of the total of 100 patients, there were 28 who consumed psychoactive substances. The average age of patients from group one was 28, which is significantly lower than the age of patients from the second group. Another significant difference was noted between men and women, with 82.1% men consuming psychoactive substances. There were 50% of patients from group one who were prescribed with mood stabilizers, while only 26.4% of patients from the second group had mood stabilizers in their therapy. There were no other significant differences in demographic and clinical characteristics between the two groups of patients. Conclusion: Mood stabilizers were used more often in patients who consumed psychoactive substances. There were no other significant differences between the observed groups.