Tetramine toxicity due to sea snail ingestion is generally mild and has a good prognosis. Tetramine toxicity acts on the acetylcholine receptor, affecting the neuromuscular junction and autonomic nervous system. A 78-year-old female patient visited the emergency room with vomiting and dyspnea after eating sea snails. At the time of admission, the vital signs recorded were 140/80 mmHg-105/min-24/min-36.5℃, and 90% oxygen saturation. Arterial blood test revealed hypercapnia (pCO2 58.2 mmHg) and respiratory acidosis (pH 7.213, HCO3- 22.5 mmol/L), whereas other blood tests showed no specific findings. Due to decreased consciousness and hypoxia, endotracheal intubation and mechanical ventilation were administered to the patient. Successful weaning was accomplished after 12 hrs, and the patient was discharged without any further complications. Although tetramine toxicity rarely results in acute respiratory failure due to paralysis of the respiratory muscle, caution is required whilst treating the patient.