All antithrombotic drugs confer a risk of bleeding. In addition to its antiplatelet effect, COX1 inhibition by aspirin in the stomach can lead to acid-induced inflammation and ulceration, resulting in bleeding. There is evidence that lower doses of aspirin are associated with lower rates of gastrointestinal bleeding (Valkhoff, Sturkenboom et al. 2012) including when combined with a P2Y12 inhibitor (Mehta, Tanguay et al. 2010).