Clopidogrel and aspirin are different in exerting the mechanism of action of antiplatelet aggregation, efficacy, contraindications, and causing adverse reactions. 1. Mechanism of action. Clopidogrel’s anti-platelet aggregation mechanism is to inhibit the activation of fibrinogen receptors, thereby inhibiting platelet aggregation. Aspirin is a cyclooxygenase inhibitor, which can inhibit the activity of cyclooxygenase, block the synthesis of thromboxane A2, increase prostacyclin, and play the role of anti-platelet aggregation. 2. Efficacy: Compared with clopidogrel, aspirin not only has the effect of anti-platelet aggregation, but also has the effect of anti-inflammatory, antipyretic and analgesic. 3. Contraindications: Clopidogrel is contraindicated in patients with ulcer disease and intracranial hemorrhage. Aspirin is contraindicated in patients with hepatic or renal insufficiency, cardiac insufficiency and hemophilia. 4. Adverse reactions. Long-term use of clopidogrel can cause adverse reactions such as nasal skin mucous membrane bleeding and gastrointestinal bleeding. Long-term use of aspirin generally causes nausea, abdominal pain, diarrhea and other gastrointestinal reactions, and even cause serious adverse reactions such as black stools. It is important to note that it is contraindicated for those who are allergic to these two drugs and must be taken under medical supervision.