Rarely listed essential medicines in 158 national lists.

Background: Health needs are relatively similar across the planet as there are few conditions that are truly unique to one region or country, and most conditions are common around the world. Differences in health needs do not explain differences in national essential medicines lists. Factors other than health needs may well lead different countries to select different medicines. The purpose of this study is to identify and describe medicines listed by only a small number of countries. Methods: Using the Global Essential Medicines database of NEMLs that was updated in 2023 and 2025, we identified medicines listed by 2 or fewer countries that were not listed on the 2023 World Health Organization's Model List of Essential Medicines. We characterized these rare medicines and their indications based on information obtained from the NEMLs that listed them, and also performed literature searches for each rarely listed medicine. We also identified which countries listed many rare medicines (5 or more) and performed literature searches to explore possible explanations for them being rarely listed. Results: We identified 460 rarely listed essential medicines, including 317 medicines that were listed in the NEML of only one country, and 143 medicines that were listed by two countries. A total of 83 countries listed at least one rare medicine, including 30 countries that listed many (5 or more) rarely listed medicines and 53 that listed few rare medicines. Countries that listed many rare medicines included Greece, Australia, and the Russian Federation. Conclusion: Certain medicines are prioritized for access in just one or two countries, and some countries list many such medicines. Further work is needed to understand why certain medicines are rarely listed and whether changes to lists are needed.