In recent years, severe or lethal cases of caffeine poisoning after large or massive ingestion of caffeinated tablets have increased in Japan. Here we report the case of a 23-year-old male who ingested high-dose caffeine tablets (total: 32.4 g caffeine) in a suicide attempt. He was transferred to our hospital about 2 h after ingesting the tablets and presented with repeated vomiting and tremor in the trunk and extremities. His respiratory rate was 40 breaths/min, heart rate 240 beats/min, blood pressure 109/77 mmHg, and Glasgow Coma Scale E3V2M5. Blood tests revealed metabolic acidosis compensated with respiratory alkalosis, hyperlactatemia, hypokalemia, hyperglycemia, and leukocytosis. After tracheal intubation, gastric lavage was performed and activated charcoal was administered. The patient gradually became hypotensive (systolic blood pressure < 90 mmHg) with a heart rate > 250 beats/min, and non-sustained ventricular tachycardia frequently occurred. Given the lack of response to intravenous noradrenaline and landiolol, high flow continuous hemodialysis (CHD) was initiated 4 h after tablet ingestion with a blood flow rate of 150 mL/min and dialysate flow rate of 2000 mL/h. This dramatically improved his clinical signs and symptoms, especially during the first 3 h. His serum caffeine concentration was 240.9 μg/mL on admission and 344.0 μg/mL at the initiation of high flow CHD, but rapidly decreased to 153.8 μg/mL 3 h after initiating high flow CHD. Our findings suggest that high flow CHD may be effective in treating cases of severe caffeine poisoning with hemodynamics too unstable for intermittent hemodialysis.