Purpose: The international drug classification systems are very helpful tools in the managing process of drugs and drug related information. This narrative review study aims to survey and compare the characteristics and applications of these systems. Methods: In order to identify the international drug classification systems, a search was done in 2019 and in various sources, including PubMed and Scopus databases, as well as Google Scholar search engine, drug databases, specialized websites and electronic files containing information about the system. The search strategy consists of the keywords Drug, Classification system, Coding system and International along with their synonyms. Systems were entered into the study for which information was available. These systems were examined and compared in terms of release date, classification domain, developer organization, basic framework, system structure, code structure and updating period. The main applications of these systems were also extracted. Results: The search resulted in 10 international drug classification systems, ATC/DDD, ATCvet, HerbalATC, AT-EphMRA, NFC, AHFS, PCNE, UNSPSC, ICPM and ICD-10. Forty percent of systems, classify certain groups of medicines or specific drug information such as herbal medicines, veterinary medicines, medication forms, and drug related problems. All of these systems have been developed by authoritative international organizations and have hierarchical structure. The most significant applications of these systems are to identify drug products, monitor and compare medication usage and study drug related problems. Conclusion: The international drug classification systems have been developed to classify different drug groups and their information. However, none of them comprehensively cover all the drug information. Therefore, the development of a comprehensive international drug classification system can be a good way to use these systems more effectively in drug management.