Dipyridamole inhibits phosphodiesterase, which increases platelet cyclic adenosine monophosphate (cAMP) and results in inhibition of platelet function. It is used in combination with warfarin to prevent thromboembolism in patients with prosthetic heart valves, and in combination with aspirin for secondary prevention of ischaemic stroke and transient ischaemic attack. It does not cause bleeding, and neither does it increase the incidence of aspirin-related bleeding. Dipyridamole should be started at a low dose. A combination formulation of controlled-release dipyridamole 200 mg and aspirin 25 mg is available, and is the most common formulation of dypridamole used. Caution should be exercised if considering the use of this product with other antiplatelet agents and anticoagulants, as there is an increased risk of bleeding.

Adverse effects include headache, flushing, nausea and gastrointestinal upset.