PURPOSE: There are a limited number of case reports in the literature which describe hyponatremia/syndrome of inappropriate antidiuretic hormone (SIADH) induced by duloxetine. SUMMARY: This case report adds to the literature by describing a patient who developed hyponatremia/SIADH after two doses of duloxetine. CONCLUSION: Hyponatremia/SIADH can develop rapidly after initiation of duloxetine. Clinicians should be aware of the potential for this adverse drug reaction, particularly in elderly females.