In many cases, the hyponatremia appears to be caused by the syndrome of inappropriate antidiuretic hormone secretion (SIADH). This, however, may reflect clinical practice in which some people, due to pressure of time and dislike of venipuncture, do not have samples taken for assay. We are grateful to Gail Bell for reviewing the manuscript.BB, JvdP, GJdH, DL, and BK report no disclosures. Hyponatremia is one of the most frequent electrolyte disorders associated to medication, being those drugs prescribed for psychological or neurological disorders the most dangerous ones in this sense 1.. Carbamazepine and oxcarbazepine are antiepileptic drugs which can induce hyponatremia, an adverse effect usually asymptomatic in the setting of these dugs 2,3.. Carbamazepine (CBZ), a commonly prescribed medication in psychiatry and neurology, produces deleterious side effects with an incidence rate ranging from 33–50%; although most of these side effects are mild, transient, and reversible. Hyponatremia was symptomatic in 48% and led to admissions in 3%. The retard tablets (whole pill or half if prescribed by a doctor) should be swallowed without chewing, with a small amount of liquid. We have seen a relatively high frequency of severe hyponatremia, especially in those treated with OXC. Oxcarbazepine and carbamazepine cause hyponatremia by unknown mechanisms. Carbamazepine (Carba) is an anticonvulsant and psychotropic drug used widely for the treatment of intellectual disability and severe pains, but the incidence of hyponatremia is a common related occurrence. insulin-dependent diabetes, associated with cerebral disorders, with polyuria and polydipsia associated with neurohormonal shifts. Thus, the association of CBZ dosage or serum level with hyponatremia remains unclear. CBZ-induced hyponatremia is a moderately well described side effect and may be responsible for some of the more highly reported signs and symptoms associated with CBZ adverse effects.2. Sodium levels were measured and recorded in 1,132 (79%) treated with CBZ (616 male) with a mean age of 41.8 ± 15.6 (years ± standard deviation [SD]) and a mean Na+ level of 138.4 ± 4.2 mEq/L. Among those who were symptomatic, 6% had CBZ or OXC levels above the therapeutic range (10 with CBZ levels ≥11, one with OXC level ≥35). The risk of hyponatremia on CBZ was significantly associated with the risk of hyponatremia on OXC within a subgroup that used both drugs consecutively.Hyponatremia is a common problem in people taking CBZ or OXC. If clinical sxs -- HA, nausea, fatigue, confusion -- then I reduce the dose; other meds incl SSRIs may worsen this, as well. dosage regimen, carbamazepine extended-release tablets afford steady-state plasma levels comparable to conventional carbamazepine tablets given q.i.d., when administered at the same total mg daily dose. The risk of developing SIADH with Carbamazepine treatment appears to be dose-related. Stichting Epilepsie Instellingen Nederland (SEIN), Zwolle, The NetherlandsDepartment of Epidemiology, Medical School Twente, Enschede, The NetherlandsDepartment of Research Methodology, Measurement and Data Analysis, University of Twente, Enschede, The NetherlandsStichting Epilepsie Instellingen Nederland (SEIN), Zwolle, The NetherlandsStichting Epilepsie Instellingen Nederland (SEIN), Zwolle, The NetherlandsDepartment of Genetics, University Medical Center Utrecht, Utrecht, The NetherlandsDepartment of Genetics, University Medical Center Utrecht, Utrecht, The NetherlandsStichting Epilepsie Instellingen Nederland (SEIN), Zwolle, The NetherlandsNIHR UCL Hospitals Biomedical Research Centre, UCL Institute of Neurology, London, United KingdomChalfont Centre for Epilepsy, Chalfont St. Peter, United KingdomStichting Epilepsie Instellingen Nederland (SEIN), Zwolle, The NetherlandsDepartment of Epidemiology, Medical School Twente, Enschede, The NetherlandsDepartment of Research Methodology, Measurement and Data Analysis, University of Twente, Enschede, The NetherlandsStichting Epilepsie Instellingen Nederland (SEIN), Zwolle, The NetherlandsStichting Epilepsie Instellingen Nederland (SEIN), Zwolle, The NetherlandsDepartment of Genetics, University Medical Center Utrecht, Utrecht, The NetherlandsDepartment of Genetics, University Medical Center Utrecht, Utrecht, The NetherlandsStichting Epilepsie Instellingen Nederland (SEIN), Zwolle, The NetherlandsNIHR UCL Hospitals Biomedical Research Centre, UCL Institute of Neurology, London, United KingdomChalfont Centre for Epilepsy, Chalfont St. Peter, United KingdomUse the link below to share a full-text version of this article with your friends and colleagues.