A 17-year-old female presented with retrosternal and epigastric burning after consuming 50ml of bleach containing sodium hypochlorite. Her initial ECG showed first-degree AV block with a prolonged PR interval of 320ms that normalized to 140ms on a follow up ECG 3 days later, likely after elimination of the toxin. First-degree AV block is defined as a PR interval over 200ms and can be caused by various conditions. It typically has no symptoms but may reduce exercise tolerance and cause syncope in rare cases of infranodal block or left ventricular dysfunction. Treatment involves discontinuing any medications that may cause AV block and permanent pacing may be indicated in severe cases.