Introduction Hydroxychloroquine (HCQ) is an antimalarial agent that has been tried out in the treatment of COVID-19, however, evidence of efficacy remains limited. Although Hydroxychloroquine overdose is not common, growing cases of poisoning with HCQ have been reported during recent years. HCQ toxicity is characterized by life-threatening symptoms which require immediate medical intervention. This report presents a suicide attempt in a hyperglycemic patient, massive ingestion of HCQ manifested by hypokalemia and acidosis.Case summaryA 47-year-old man presented at the hospital hours after massive ingestion of HCQ (100 tablets), with generalized weakness and dizziness which had led to a fall. He was drowsy and had experienced episodes of nausea/vomiting. His past medical history was remarkable for uncontrolled diabetes mellitus, confirmed by the blood glucose of 345 mg/dL, and a previous history of hospitalization a few months ago, due to a suicide attempt. He developed marked hypokalemia accompanied by acidosis, plasma potassium of 2.8 mmol/L and pH 7.34, and hypotension, blood pressure of 80/51 mm Hg, but survived with close cardiac monitoring and immediate intervention including aggressive potassium replacement, bicarbonate infusion, and charcoal administration. ConclusionConsidering the significantly increased off-label use of HCQ during the COVID-19 pandemic, this report alerts the potential for HCQ to be associated with severe electrolyte disorders, especially in predisposing conditions like diabetes. Clinicians should keep in mind the possibility of hypoglycemia in diabetic patients under hypoglycemic medications and concurrent use of chloroquine/HCQ. This therapeutic approach also suggests the benefit of even a delayed activated charcoal administration in the treatment of HCQ poisoning.