A case report: Serotonin syndrome induced by tramadol, which was difficult to diagnose due to the combined use of olanzapine

Abstract

Reports of serotonin syndrome are increasing due to the increased use of serotonergic agents. We report the case of a patient in whom the combined use of olanzapine and tramadol, which has a serotonin-noradrenaline re-uptake inhibitor (SNRI) effect, resulted in difficulty in diagnosing serotonin syndrome. This was due to the poor recognition that tramadol has a SNRI effect and the initial use of Sternbach’s diagnostic criteria instead of Hunter’s diagnostic criteria to diagnose serotonin syndrome and because olanzapine suppressed sympathetic nerve stimulation symptoms such as fever. Serotonergic agents are widely used in the psychiatric field. Therefore, psychiatrists should have extensive knowledge about serotonin syndrome, including the serotonergic agents used in other areas, diagnostic criteria, etiology hypotheses, and treatment.