The chemical name of alum is potassium aluminum sulfate dodecahydrate, which has been banned from use in food additives in China. Alum can be used as a traditional Chinese medicine with certain pharmacological effects, as follows: 1, antibacterial, alum has inhibitory effects on a variety of gram-negative bacteria, gram-positive bacteria, cocci and bacilli, and also has strong antibacterial effects on common septic bacteria; 2, astringent, solid off, alum water has a strong astringent effect, usually used externally to stop sweating; 3, anti-vaginal trichomonas; 4, cholagogic. Because of its local topical irritation, alum is usually diluted before use in the process of antiperspirant.