Context

Trimethoprim–sulfamethoxazole (TMP–SMX) is a combination antibiotic used for a number of infectious diseases and organisms.1 It is generally well tolerated; however, electrolyte disturbances, primarily hyperkalaemia, have been reported with both standard and high-dose therapy.1 ,2 Spironolactone, an aldosterone receptor antagonist, predominantly used in the management of heart failure and cirrhosis, is also known to cause hyperkalaemia.3 The risk of developing hyperkalaemia during co-administration of these two commonly prescribed medications is unknown. Antoniou et al describe the association between hospitalisation for hyperkalaemia and prior use of TMP–SMX in an older population receiving spironolactone.