Introduction: Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) used in the treatment of depressive disorders. Cardiotoxicity and neurotoxicity have rarely been attributed to the use of fluoxetine. Several clinical studies showed that fluoxetine is less likely to cause significant cardiovascular toxicity even in overdose. Other studies showed that ingestions of 40–800 mg fluoxetine have generally produced minimal toxicity in adults. Of note, fluoxetine and ibuprofen increase toxicity of each other by pharmacodynamic synergism.
Case Report: This is the case of widened QRS duration in a 21-year-old female with background depression. She had taken a mixed overdose of fluoxetine (600 mg), omeprazole (600 mg), ibuprofen (1200 mg), metronidazole (unclear amount). On admission she was hallucinating, profoundly agitated, tachycardic with a heart rate of 128 bpm, new broadening in QRS complex to 134 ms on electrocardiography, corrected QT (QTc) was 616 ms. Following discussion with TOXBASE, she was given 2 g magnesium sulfate, 1.4% sodium bicarbonate, admitted to high dependency unit for cardiac monitoring. She also needed sedation.
Conclusion: This case is interesting from the point of view of broad complex tachycardia that could result in cardiac arrest due to a prolonged QTc of 616 ms, as well as the visual and auditory hallucinations the patient had. It also raised the question of possibility of pharmacodynamic drug-drug interaction in which ibuprofen could have via synergism, potentiated the cardiotoxic effects of an otherwise generally safe SSRI; fluoxetine.

Keywords: Complex drug-drug interactions, ECG abnormalities, Fluoxetine overdose, Hallucinations, Prolonged QTC, SSRI overdose