Records in PubMed have been assigned subject headings, a controlled vocabulary called Medical Subject Headings or MeSH for short. These are used to index citations allowing you to retrieve all records on a particular subject regardless of the terminology used by the author. For example, a search for the subject heading Myocardial Infarction will retrieve records that include terms such as heart attack, acute myocardial injury and myocardial infarction including any variant spellings and plurals. Narrower, more specific MeSH terms will also be searched for such as ST Elevation Myocardial Infarction.
A simple PubMed search automatically searches for MeSH terms. However, you can also carry out your own searches using the MeSH database if you wish.
In order to have more control over your search strategy you can search for MeSH terms directly in the MeSH database and use the Advanced Search to combine your searches.
Access the MeSH database from the PubMed homepage. Please note that the MeSH database has not been updated to match the technology used in the new PubMed so your searching experience will look quite different when you move between the two interfaces.
When you find a relevant article in PubMed you can examine its MeSH terms to help you identify those that you could use in your search strategy. You will find an article's MeSH terms when looking at its full record or Abstract view.
Prior to April 2022, the majority of MEDLINE records were indexed by human indexers. Due to the vast number of articles being added to the database there were significant time delays in the process. To speed things up, since April 2022 all MEDLINE records in PubMed are assigned MeSH terms using automated indexing. Human indexers still check the quality of selected sets of automatically indexed citations.
You can read more about how MeSH records are assigned using this new process in the NLM Automated Indexing FAQs.