Metformin is a medicine used as first-line treatment in type 2 diabetes mellitus, its mechanism of action includes among others: preventing the production of hepatic glucose, decreases the transport of glucose at intestinal level. One of its adverse effects is lactic acidosis, especially when its used in autolytic attempts. Mortality in these patients is still high despite modern treatment with renal replacement therapy.Case presentation: We present the case of a 16-year-old female patient who entered the emergency service due to metformin poisoning (30 tablets of 500mg) secondary to autolytic attempt. The patient was drowsy, with increased hydroaereal noises, and relaxation of sphincters. Gasometric controls showed rising lactate figures, reaching values of up to 19.5 mmol/L. Patient required invasive mechanical ventilation which is why, entered the intensive therapy service for management of multiorgan failure, renal replacement treatment was initiated with prolonged cycles. Patient was discharged from intensive care on her fifth day of hospitalization and continued her treatment in charge of the internal medicine service.Conclusions: Metformin being a widely used medicine worldwide, every emergency service should be prepared to identify cases of this drug. Interventions include: fluid therapy, vasoactive drugs, invasive ventilatory support, sodium bicarbonate, and renal replacement therapy; All of them were provided to our patient with successful results.