Clopidogrel can inhibit platelet aggregation and is a commonly used drug in the treatment of coronary heart disease and cerebrovascular disease. Clopidogrel does not have the most contraindicated conditions, and should not be used in allergy, severe liver and kidney injury and suffering from bleeding disorders and other people. 1. Allergy: patients who are allergic to the components of clopidogrel may suffer from itchy skin, rash and other manifestations in the less severe cases, and in the more severe cases, they may suffer from systemic damages such as anaphylactic shock, or even life-threatening. 2. Serious liver and kidney injury: Clopidogrel is metabolized by the liver and excreted by the kidneys, therefore, if patients suffering from serious liver and kidney injury use this drug, it will aggravate the burden on the liver and kidneys and worsen the condition. 3. Bleeding disorders: clopidogrel has an anti-platelet effect, which will aggravate the bleeding symptoms of active bleeding disorders. Patients suffering from active peptic ulcer, intracranial hemorrhage and other diseases, clopidogrel is prohibited, so as not to cause hemorrhage. In addition, the drug is not suitable for use during pregnancy in pregnant women. Patients should exclude relevant contraindications under the guidance of a doctor before using Clopidogrel. Common adverse reactions of Clopidogrel include nosebleed, dyspepsia, abdominal pain and diarrhea, etc. If you feel unwell during the course of taking the drug, you should seek medical advice to clarify the cause.