Loperamide-Induced Ventricular Arrhythmia and Seizures

Loperamide-induced cardiotoxicity can occur when taken at high doses.

A 42-year-old man presented with polymorphic ventricular tachycardia after taking 100 to 200 mg of loperamide daily to self-treat opioid withdrawal. The presenting electrocardiogram showed a wide complex rhythm which spontaneously converted to sinus rhythm with a prolonged QT interval. Implantable cardiac-defibrillator therapies treated polymorphic ventricular tachycardia and ventricular fibrillation. Loperamide was discontinued, and he was treated for opioid use disorder.

Loperamide can cause cardiotoxic manifestations such as acquired long QT syndrome with associated ventricular arrhythmias and neurologic manifestations such as seizures.

Although loperamide is an over-the-counter medication, life threatening cardiotoxicity and neurotoxicity can occur with high doses.