Searching the MeSH Thesaurus

MeSH (Medical Subject Headings) is a controlled vocabulary of biomedical terms used for indexing documents in MEDLINE. MeSH was developed and is maintained by the National Library of Medicine the producer of MEDLINE.

You must use subject headings to search the MeSH Terms field in MEDLINE. Qualifiers, also known as subheadings, are controlled terms that qualify or add context to subject headings. The thesaurus also contains non-preferred or entry terms that serve as access points to subject headings.


Find Option

  1. Enter a word, phrase, or text string in the text box. Boolean operators (AND, OR, NOT) and wildcards (* $ ?) are permitted.

  2. Click the Find button to display a list of thesaurs terms.

  3. Click the Add button to select a term from the list. The selected item is added to the text box at the bottom of the page.

  4. Click OK to transfer the item(s) to the Search page. If performing an Advance Search, the product transfers the selected item(s) to the field box on the Advanced Search page along with the correct field tag.

The Add button next to a term in the thesaurus indicates that the term is a subject heading or qualifier.

After you click the Find button, the product displays a list of substances. A substance will be on the list if: 1) The search term matches the name or part of the name of a substance, or 2) The search term is found in the Entry Term field.

See also Subject Heading Details.


MeSH Hierarchy

Subject headings are arranged in hierarchies. The broadest terms (for example, Anatomy, Diseases) are at the top of the hierarchy. These broad subject headings do not have the Add button, and so they should not be used to search the MeSH Terms field.

The other hierarchy in MeSH is the qualifier hierarchy. Use qualifiers to refine your search by subject heading. For example, if you add the qualifier drug therapy to the subject heading Osteoporosis, you will retrieve records of documents that discuss drug therapies for the treatment of osteoporosis.


Browsing a Hierarchy

Subject headings are arranged in hierarchies. Often multiple subject headings describe a concept such as a disease state at varying levels of specificity. The more familiar you become with MeSH the more targeted your searches can be.

  • Click the Expand Term Expand Term icon icon to expand the hierarchy and reveal additional terms. Use the scroll bar on the right-hand side of the page to move up and down the list of expanded terms. Click Collapse Term icon to collapse the hierarchy.

  • Click the View in Hierarchy View in Hierarchy icon icon to see a term in the context of its hierarchy.

  • Click the View Details View Details icon icon to view details about a term. Details include scope notes and related terms. Details are available for both subject headings and qualifiers.


Adding Qualifiers

When you click the Details Details icon icon to view the details of a subject heading, you can find a list of qualifiers that can be added to the subject heading. You add qualifiers to add meaning or context to the subject heading. For example, if you add the qualifier biosynthesis to the subject heading Riboflavin, you will search for documents that discuss the biosynthesis of this vitamin.

To add a qualifier, click the Add button next to the qualifier. You do not need to add the subject heading first. Adding the qualifier automatically adds the subject heading and the qualifier to the text box at the bottom of the page.


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