Searching PubMed using MeSH® Field Tags
Untagged terms that are entered in the PubMed search box are automatically mapped to the MeSH vocabulary when a match is found. However, you may choose to search the MeSH headings specifically using search field tags (also called qualifiers).
Note: Searching with MeSH subject terms excludes in process and publisher-supplied citations and others that do not (or do not yet) include MeSH subject terms.
MeSH headings [MH]
- MeSH headings can be qualified using two search field tags:
[mh] to search a MeSH heading
[majr] to search a MeSH heading that is a major topic of an article
Examples: | eye [mh] eye [majr] |
- PubMed automatically searches the MeSH headings as well as the more specific terms beneath that heading in the MeSH hierarchy. This is known as the explosion feature.
Example: | eye [mh] will retrieve citations indexed to: |
Eye and all more specific terms underneath these in the hierarchy. |
- To turn off automatic explosion of MeSH headings, use one of the following tags:
[mh:noexp] or [majr:noexp]
Example: eye [mh:noexp] This retrieves citations indexed with the term, Eye – but not necessarily indexed with the terms beneath that heading in the MeSH hierarchy. Remember that indexers use the most specific MeSH heading to describe the subject of a journal article.
Subheadings [SH]
- A list of subheadings can be found in PubMed's Help.
- MeSH specialists and indexers determine which subheadings may be used in combination with each MeSH heading. These combinations may change over time.
- For searching, attach subheadings to MeSH headings using the format: MeSH heading/subheading.
- Two-letter abbreviations for subheadings or the full subheading name may be used.
Examples: | thromboembolism/pc [mh] thromboembolism/prevention and control [mh] toes/in [majr] toes/injuries [majr] |
- Only one subheading may be attached to a MeSH heading at a time. To attach multiple subheadings, combine each MeSH/subheading combination with the OR Boolean operator or use the MeSH Database, which allows multiple subheadings to be selected.
Example: To search for citations where the main topics are about the prevention and control or diagnosis of thromboembolism, enter: thromboembolism/pc [majr] OR thromboembolism/di [majr]
- For a MeSH/subheading combination, PubMed always explodes the MeSH term and also searches the subheading and its grouping if there is one. You cannot explode a MeSH heading and not also explode the attached subheading.
Example: polysaccharides/ae
Retrieves citations indexed with any of the polysaccharides with any of these subheadings:
ae (adverse effects)
po (poisoning)
to (toxicity)Note: polysaccharides/ae [mh:noexp] turns off both the MeSH heading explosion and the subheading explosion.
Unattached subheadings
- You may also choose to search a MeSH heading and a subheading combination using the AND Boolean operator and the subheading field tag of [sh]. This may be done when you want to search for a subheading concept that cannot “legally” be attached to the MeSH heading you are also searching.
Example: hypertension [mh] AND toxicity [sh]
- To turn off the subheading grouping, use the tag [sh:noexp]. Do this only when using an unattached subheading.
Example: finger injuries [mh] AND surgery [sh:noexp]
PubMed’s Help includes:
See also:
Subheading (Qualifier) Hierarchy