We report a case of cardiac arrest in a young man in his late teens that was caused by overdoses of drugs (including cibenzoline, class Ia antiarrhythmic agent), which were prescribed for his family. He had no history of past illness, including any type of psychiatric disorder. The patient took 30 cibenzoline (100 mg) tablets, 118 valproate sodium (200 mg) tablets, 28 brotizolam (0.25 mg) tablets, and 34 ibuprofen (100 mg) tablets in his home. He was transported to our emergency department 70 minutes after taking these drugs. While an electrocardiogram showed complete right bundle branch block, he had stable hemodynamics at the time of admission. Fifteen minutes after his arrival, the electrocardiogram indicated ventricular tachycardia and eventually led to pulseless electrical activity. A percutaneous cardiopulmonary support device was used because of ineffectiveness of advanced cardiac life support. After admission to the intensive care unit, he was treated with plasma exchange and percutaneous cardiopulmonary support. His cardiac output then gradually increased. He recovered with no neurological sequelae and was discharged from the hospital 10 days after admission. Class Ia antiarrhythmic agent intoxication caused by an overdose is rare. Clinicians should be able to treat this intoxication based on the mechanism of action. In severe cases, as the initial response, physicians should consider using mechanical circulatory support when there is acute circulatory insufficiency. Additionally, appropriate blood purification therapy should be selected if required.