Hyponatraemia and selective serotonin reuptake inhibitors

Part 1 describes the case of a 74‐year‐old woman who experienced a worsening of her psychiatric condition shortly after commencing fluoxetine and was found to have a low serum sodium level. The clinical features of hyponatraemia and its causes are reviewed. Part 2 reviews the reports of hyponatraemia and the selective serotonin reuptake inhibitors (SSRIs) and considers the variation in reports between the different SSRIs. Measurement of a patient's electrolytes is recommended if there is a rapid decline in mental state having started on an SSRI.