one of the most frequently used pain relievers is acetylsalicylic acid which is commonly.An aspirin tablet contains more than aspirin, however.Manufacturers mix aspirin with starch, which keeps the tablets from falling apart and makes them large enough for easy handling. Furthermore,aspirin can break down into salicylic acid and acetic acid over time. Therefore, an aspirin tablet is a mixture of at least four substances: aspirin,starch,salicylic acid,and acetic acid.