Drugs causing hyponatraemia

Drug-induced hyponatraemia occurs in approximately 5% of outpatients and 15% of inpatients. The commonest drugs causing hyponatraemia are: (1,2)

• desmopressin, oxytocin
• medications that stimulate vasopressin release or potentiate the effects of vasopressin: selective serotonin-reuptake inhibitors and most other antidepressants,​​ morphine and other opioids
• medications that impair urinary dilution such as thiazide diuretics
• medications that cause hyponatraemia by an uncertain mechanism of action such as carbamazepine, vincristine, nicotine, antipsychotics, chlorpropamide, cyclophosphamide, non-steroidal anti-inflammatory drugs
• illicit drugs: MDMA or ecstasy causes vasopressin release, and has been associated with acute, life-threatening hyponatraemia
• bowel preparations for colonoscopy

Most patients with hyponatraemia are diagnosed incidentally on routine blood tests

Example causes of drug induced hyponatraemia:

Reference:

1. Adrogué HJ, Tucker BM, Madias NE. Diagnosis and management of hyponatremia: a review. JAMA. 2022 Jul 19;328(3):280-91.
2. Grant P, Ayuk J, Bouloux PM, et al. The diagnosis and management of inpatient hyponatraemia and SIADH. Eur J Clin Invest. 2015 Aug;45(8):888-94.