Hyponatremia is an antidepressants known adverse effect, ADH secretion has been postulated in its etiology.

To identify risk factors for hyponatremia induced by antidepressants and psychopharmacologic alternatives.

Literature search was performed in PubMed. We report of a case of recurrent hyponatremia treated in our center: woman, 57years old, HIV, HCV; performing 4 episodes of severe hyponatremia in 5 months of treatment involving thiazide, venlafaxine, citalopram, olanzapine,haloperidol, enalapril, escitalopram.

Risk of hyponatremia is higher in patients treated with antidepressants (OR = 2.97), especially serotoninergic antidepressants (OR = 3.96). Elderly and thiazide increment that risk (OR = 6.31 and OR = 8.4 respectively), specially age, thiazide and SSRIs (OR = 148). Higher prevalence in females, lower limit levels of sodium and low body weight. All SSRIs are likely to produce hyponatremia. The effect appears in the first month, it's not dose-dependent and recovers by interrupting treatment. Some cases have been reported following re-exposure to the same or different antidepressant: fluvoxamine and paroxetine (Arizon, 2002), duloxetine and escitalopram (Stovalle, 2009), sertraline and fluoxetine (Raphael, 2010), sertraline and citalopram (Pure, 2011).

Early detection is important, as well as the evaluation of concomitant risk factors in all patients starting antidepressant. Some asymtomatic cases can be unnoticed by clinicians, so risk patients it seems necessary to control ion pretreatment periodically, and to chose safer treatments (bupropion, agomelatine, mirtazapine and reboxetine). In our case, age, sex, concomitant diseases, low sodium and low weight were determinants for the recurrence of the disorder.