What Are MeSH Terms in PubMed?

MeSH (Medical Subject Headings) is the National Library of Medicine's controlled vocabulary used to index articles in MEDLINE and PubMed. Indexers assign MeSH terms to describe what an article is about, so searching a MeSH term can retrieve relevant articles even when the authors used different words.

How MeSH is organised

• Descriptors: the main headings, arranged in a hierarchy (a tree) from broad to specific.
• Entry terms: synonyms that point to a descriptor, so a search for a synonym finds the same heading.
• Subheadings (qualifiers): narrow a descriptor to an aspect, such as therapy, diagnosis or adverse effects.
• Explosion: by default, searching a MeSH heading in PubMed includes narrower terms beneath it in the tree.
• Major topic: you can restrict to articles where the heading is a main focus.

How to find MeSH terms

1. Search the MeSH database for your concept.
2. Check the definition and tree position.
3. Add the term to the PubMed search builder.
4. Note related terms that might also be relevant.

Why also use free text

New articles may not be MeSH-indexed yet, and some records are not indexed at all (for example publisher-supplied records), so relying on MeSH alone can miss papers. Combine MeSH with title/abstract synonyms.

Illustrative example

Invented for teaching. For "heart attack", you would use the MeSH heading "Myocardial Infarction" together with free-text terms such as "heart attack"[tiab] and "myocardial infarct*"[tiab]. The MeSH heading captures articles using "STEMI" or "acute coronary event" if indexers placed them under the heading.

Common pitfalls

• Choosing a MeSH heading that is too broad or too narrow.
• Forgetting that indexing can lag for new articles.
• Using subheadings without understanding that they limit results.

Key takeaways

• MeSH is controlled vocabulary assigned by NLM indexers.
• Combine it with free-text terms for sensitivity.
• Check the MeSH Browser for current terms and definitions.

This page is general educational information about research methods. It is not medical, legal or regulatory advice; follow your institution's ethics board and your target journal's instructions.