Aspirin [Aspirin,2-(acetoxy) benzoic acid, also known as acetylsalicylic acid] is a white crystal or crystalline powder, odorless or slightly acetic acid odor, slightly soluble in water, soluble in ethanol, soluble in ether, chloroform, aqueous solution is acidic. This product is a derivative of salicylic acid. It has been proved to be effective in relieving mild or moderate pain, such as toothache, headache, neuralgia, muscle soreness and dysmenorrhea. It is also used to relieve fever such as cold and flu, and treat rheumatic pain. In recent years, aspirin has been found to inhibit platelet aggregation and prevent thrombosis. It is clinically used to prevent the formation of thrombosis after transient ischemic attack, myocardial infarction, artificial heart valve and venous fistula or other operations.