Aspirin is a white crystal or crystalline powder, odorless or slightly smelly of acetic acid, slightly soluble in water, easily soluble in ethanol, and its aqueous solution is acidic. This product is a derivative of salicylic acid. After nearly a hundred years of clinical application, it has been proved to be effective in relieving mild or moderate pain, such as toothache, headache, neuralgia, muscle pain and dysmenorrhea. It is also used for colds, flu, etc. Antipyretic of febrile diseases, treatment of rheumatic pain, etc.