Asymptomatic syndrome of inappropriate secretion of antidiuretic hormone (SIADH) following duloxetine treatment for pain with depression: Two case reports

BACKGROUND: Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is a common side effect in patients treated with SSRIs and venlafaxine, while there is little information on SIADH in the treatment of duloxetine for pain. CASE PRESENTATION: The patients were an 83‐year‐old Japanese male and a 71‐year‐old Japanese female. Several years earlier, they complained of pain. Accidentally, blood tests revealed hyponatremia of 110 mmol/L and 108 mmol/L 35 days and 40 days after initiating duloxetine 20 mg/day, respectively. The hyponatremia of both patients recovered after switching from duloxetine to mianserin. CONCLUSION: We conclude that asymptomatic SIADH was induced by use of duloxetine. Psychiatrists should be aware of this syndrome.