Acetylsalicylic acid × Digoxin

Like other NSAIDs, aspirin reduces renal excretion of digoxin, so digoxin blood levels rise, sometimes to toxic values (aspirin 100 mg and 500 mg SmPCs). The US digoxin label (FDA) links this to the fall in glomerular filtration and tubular secretion caused by NSAIDs. Salicylates can also strengthen the effect of digoxin through potassium and magnesium loss, because a heart short of these ions is more sensitive to digoxin (Spanish digoxin SmPC).

Signs of digoxin overdose: nausea, vomiting, loss of appetite, fatigue, visual changes with yellow-green colour vision, and rhythm and conduction disorders, from slow pulse and heart block to ventricular arrhythmias. The risk is higher in older patients, with low body weight, reduced kidney function, or low potassium or magnesium.

Aspirin SmPCs, including those for 100 mg products, do not recommend combining aspirin with digoxin. If the combination cannot be avoided, measure digoxin blood levels when aspirin is started, when its dose changes and when it is stopped (aspirin 100 mg and 500 mg SmPCs). The US digoxin label (FDA) asks for closer monitoring of digoxin levels and signs of toxicity whenever an interacting drug is started, adjusted or stopped, and for individual digoxin dosing with drugs that impair kidney function. Check electrolytes and kidney function periodically, since low potassium and magnesium raise the risk of digoxin toxicity (US digoxin label).