Syndrome of inappropriate secretion of antidiuretic hormone in patients treated with psychotherapeutic drugs.

We report two patients in whom the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) developed during the administration of psychotherapeutic drugs. In one, the syndrome occurred after administration of a phenothiazine drug and in the other, a butyrophenone. Both the patients were diagnostically studied for evidence of other disorders, either neurologic or systemic, which could cause this syndrome with negative results. They responded to fluid and free water restriction with remarkable recovery and no sequelae. It is stressed that psychotherapeutic drug administration must be considered as one of the iatrogenic causes of SIADH.