The Risks of Septra and Pronolactone in Combination

When you give trimethoprim, the end result is that people lose sodium and water, they retain some potassium. In somebody with normal kidney function or no other drugs on board, that's not a problem. But if your creatinine clearance is 30 and you're on an ACE inhibitor or you're on sopronolactone, those are the people who are at especially high risk of developing serious or even life threatening hyperkalemia.