Aspirin: How low is low dose?

Abstract

Aspirin reduces the risk of non-fatal stroke, non-fatal myocardial infarction and vascular death in patients at high risk of arterial thrombosis. Platelet function is inhibited by doses of 40-160 mg daily. In clinical trials performed before 1985, doses of 500-1500 mg daily were found to be effective. Since 1985, low doses have been evaluated and a meta-analysis has shown that daily doses of 75-150 mg are as effective as the previously used higher doses. The risk of adverse effects is dose-dependent above 75 mg daily. The maximum benefit:risk ratio is likely to be achieved with doses of 75-150 mg daily. In Australia, this is best achieved by either a single 100 mg tablet or half a 300 mg tablet taken daily.