Spironolactone Interactions

Spironolactone is a mineralocorticoid receptor antagonist that blocks aldosterone-driven potassium excretion in the collecting duct, causing the kidneys to retain potassium. Adding a potassium supplement, salt substitute, or potassium-rich diet on top of spironolactone can produce fatal hyperkalemia, especially in patients with chronic kidney disease, heart failure, diabetes, or who are also on an ACE inhibitor or ARB.

Most salt substitutes are made primarily of potassium chloride and can deliver 500 mg or more of potassium per quarter teaspoon. Spironolactone is a potassium-sparing diuretic that markedly reduces renal potassium excretion. Combining the two can cause severe, sometimes fatal hyperkalemia.

Bananas are a high-potassium food (around 422 mg per medium banana), and spironolactone is a potassium-sparing diuretic that reduces renal potassium excretion. Combining high dietary potassium with spironolactone can cause hyperkalemia, which may trigger dangerous cardiac arrhythmias.

Coconut water is naturally high in potassium (roughly 600 mg per cup) and is often consumed in large volumes for hydration. Spironolactone is a potassium-sparing diuretic that reduces renal potassium excretion. Regular high-volume coconut water consumption with spironolactone can cause hyperkalemia, including cases reported in the medical literature.

Glycyrrhizin in licorice blocks 11-beta-hydroxysteroid dehydrogenase type 2 and activates mineralocorticoid receptors - the same receptors that spironolactone is designed to block. The two work in opposite directions: licorice raises blood pressure and lowers potassium while spironolactone lowers blood pressure and raises potassium, so the herb partially undoes the drug's intended therapeutic effect.