NSAIDs can induce peptic ulcers via epithelial cell membrane disruption and the renin angiotensin system, independent of the cyclooxygenase (COX) pathways, whereas mast cells and bile acid sensors may have a protective effect on NSAID-induced gastrointestinal damage. Patients with arthritis treated with a COX-2 inhibitor are less likely to develop upper and lower gastrointestinal complications than those who are treated with diclofenac plus a proton pump inhibitor (PPI). PPI therapy is recommended in patients receiving dual antiplatelet treatment but observational studies show that clopidogrel users taking PPIs have an increased risk of cardiovascular events. Until further reliable controlled data are available, this potential, but currently unproven, clinical interaction can be minimized by widely separating the dosing of clopidogrel and PPI. Histamine-2 antagonists may be an alternative to PPI for the prevention of peptic ulcers in patients taking low-dose aspirin.