BACKGROUND: Sodium-glucose cotransporter 2 (SGLT2) inhibitors inhibit SGLT2, which is expressed in the proximal renal tubule, and thus reduce blood glucose levels by enabling the urinary excretion of excess glucose. SGLT2 inhibitors have been reported to suppress the complications of diabetes and reduce overall mortality. However, little is known about the types of symptoms that may occur in response to an overdose of an SGLT2 inhibitor. Here, we describe a case of intoxication caused by an overdose of an SGLT2 inhibitor. CASE PRESENTATION: An otherwise physically healthy adult woman ingested an overdose of ipragliflozin, an SGLT2 inhibitor, and a polypill of olmesartan medoxomil, and azelnidipine in a suicide attempt. Although her blood ipragliflozin concentration was very high (9516.3 ng/mL) upon hospital arrival, her initial blood glucose level was normal, and she did not exhibit symptoms such as hypoglycemia or polyuria. Moderate renal dysfunction associated with an estimated glomerular filtration rate of 42.3 mL/min/1.73 m2 was observed. Thirty-six hours after ingestion, her blood ipragliflozin concentration decreased to a level equivalent to that observed after a therapeutic dose and her renal function improved almost simultaneously. After improvement in her renal function, the osmotic diuretic effect of the drug progressed. Her blood glucose level declined slightly but was in the normal range due to glucose administration. During the clinical course, fatal hypoglycemia was not observed. CONCLUSIONS: Our case showed that an overdose of an SGLT2 inhibitor caused toxic effects on renal function, but severe hypoglycemia was not observed. Additional cases of intoxication from SGLT2 inhibitors alone would be helpful to clarify the mechanism of intoxication.