Over-the-Counter Loperamide Overdose Resulting in Cardiac Arrest

Over-the-counter loperamide at high doses can lead to QT prolongation and cardiac arrest.

We present a case of a woman with cardiac arrest due to ventricular tachycardia storm. Overdrive pacing, antiarrhythmic medications, and deep sedation were used to manage the recurrent ventricular tachycardia. Untargeted urine testing helped determine the etiology of the arrest may be loperamide overdose, and this was later confirmed on patient interview and targeted testing. The patient was discharged without the need for an implanted defibrillator.

Multiple over-the-counter medications, such as loperamide and diphenhydramine, can result in QT prolongation at high doses and therefore can be a cause of arrhythmia and cardiac arrest.

In cases of cardiac arrest in patients where overdose is suspected, untargeted urine testing through mass spectrometry may be helpful in determining the etiology to guide therapies and prevent unnecessary medical interventions.