Introduction: The prevalence of hypokalemia in psychiatric population is very high with eating disorders and laxative abuse being the main incriminated factors. Case presentation: We report a case of a 34-year-old woman with history of sleeve gastrectomy and breast implant, who presented for fatigue, severe myalgia, generalized hypotonia and palpitations. Laboratory exams revealed severe hypokalemia and rhabdomyolysis. The electrocardiography showed prolonged QT interval and ST segment depression with second-degree atrioventricular block. She received intravenous potassium supplementation with consecutive hydration. When potassium level was within safety limits, the patients received loop diuretics in order to decrease rhabdomyolysis and avoid kidney injury. The underlying cause was a pathological behavior, with frequent self-provoked episodes of nausea and vomiting after eating and chronic consumption of laxatives. She started psychotherapy. Conclusion: Psychiatric behaviour can lead to life-threatening conditions, therefore it should be discovered and managed promptly.