We report the case of a 45-year-old male diagnosed with mixed personality disorder brought the hospital for strange behavior. He is being treated with fluoxetine, lorazepam and topiramate; and visited his psychiatrist 72 hours ago.

He has an adequate level of consciousness and describes retrograde amnesia of the last 72 hours. We found blocks of thought and abnormal behaviors such as dressing and undressing or sorting his belongings repetitively. Urine was only positive for benzodiazepines. In arterial blood gas analysis it performed highlights compensated metabolic acidosis. After ruling out neurological diseases and administrating fluids i.v. the symptoms remitted, persisting only the amnesia, establishing the diagnosis of suicide attempt with topiramate.

The use out-of-guidelines of topiramate in personality and eating disorders is an increasingly common habit in daily clinical practice, as well as suicide attempts with this drug. In therapeutic doses, over 40% of patients taking topiramate, have asymptomatic metabolic acidosis, which in stressful situations may have clinical relevance. In case of acute poisoning, metabolic acidosis is more frequent and severe, manifesting itself by hyperventilation, hypertension and varying degrees of impaired consciousness and cognitive functions. There is also a paradoxical increase in the frequency of seizures. Treatment is supportive and there is no antidote, being lethal cases exceptional. Gastric lavage and administration of activated charcoal have limited use. The determination of plasma concentrations of topiramate is not available for most centers and is not useful in acute poisoning.