Aim: presentation of unintentional carbon monoxide poisoning in adolescents, whose care is still underdeveloped and requires a professional algorithm for effective prevention and timely treatment. Diagnostics as well as treatment procedures for acute carbon monoxide poisoning are presented in detail. Case report: A 16-year-old patient was admitted to the intensive care unit due to a disorder of consciousness of unclear aetiology. Heteroanamnesis data indicated that the patient was found unconscious in the family home, he was also hypothermic, shivering and foaming at the mouth. During the primary treatment, the patient was placed on monitoring of vital functions with oxygen on a mask and parenteral hydration. On admission, he reacted only to a painful stimulus. The laboratory findings indicated combined acidosis, with an elevated level of carboxyhaemoglobin, for the stated reason therapy with 100% oxygen was continued and the patient was diagnosed with acute carbon monoxide poisoning. The laboratory analyses revealed an elevated level of inflammatory and renal parameters with slightly elevated lactate level. No signs of pneumothorax were present on the X-ray, but initial signs of respiratory distress were present. With treatment in hyperbaric chamber and numerous supportive treatment measures, the patient was successfully cured. Conclusion: Carbon monoxide intoxication represents a diagnostic challenge, and extensive and complex treatment was described in our patient as well. Factors that significantly contribute to mortality are: the time elapsed from the patients' arrival at the emergency department to the start of treatment, the condition in which the patient arrives at the emergency department and the concentration of carboxyhaemoglobin in the patients' blood.