A 34-year-old man developed acute intoxication after an overdose of quetiapine.The man, who was receiving quetiapine for schizophrenia and depression, was admitted to an emergency unit after an overdose of quetiapine [dosage, route and time to reaction onset not stated]. He had been found unconscious by his mother. He had a Glasgow Coma Scale (GCS) score of 11, an HR of 82 beats/min and a BP of 120/80mm Hg. He also had pale skin and dry mucosa. Toxicological analysis of his urine and stomach contents found quetiapine and caffeine. He had a quetiapine blood concentration of 5.9 µg/mL, corresponding to a comatose-lethal range. A series of apnoeic pauses and seizures were observed. He subsequently had a BP of 110/60mm Hg and an HR of 130 beats/min. He had an estimated GCS score of 7.The man was admitted to an ICU and mechanically ventilated. Two hours later, his BP decreased to 75/40mm Hg. He received soya oil emulsion, charcoal haemoperfusion and atropine, with an increase in his BP and consciousness. At discharge 5 days after admission, he had a quetiapine concentration of 0.6 µg/mL.Author comment: "In the present case the patient with acute quetiapine intoxication rapidly deteriorated consciousness, breathe rate and blood pressure."