Supplementary Concept Records (also called "SCRs") are terms in a separate thesaurus from the Medical Subject Headings and are updated daily. Their purpose is to be able to add new concepts rapidly, outside of the annual MeSH review process. SCRs are mainly substances such as proteins, drugs, antibodies, toxins, and chemicals. However, there are also SCRs for treatment protocols, organisms, rare diseases, and population groups.

For example, several new Supplementary Concept Records were created in response to the COVID-19 pandemic:

• COVID-19 stress syndrome
• COVID-19 rebound
• COVID-19 breakthrough infections
• membrane protein, SARS-CoV-2

In our PubMed citation example ("Exceptional early blood pressure control rates: the ACCOMPLISH trial"), Supplementary Concept Records are listed under "Substances," and they are displayed with all lowercase letters (benazepril here).