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Searching PubMed: Searching Basics

Searching PubMed

It is helpful to know how a search is constructed.  The following can be applied to any database:

"Venn Diagram for Boolean Operator AND" by ramaxeymiles is licensed under CC BY 2.0"Venn Diagram for Boolean Operator OR" by ramaxeymiles is licensed under CC BY 2.0











"Venn Diagram for Boolean Operator OR" by ramaxeymiles is licensed under CC BY 2.0

"Venn Diagram for Boolean Operator AND" by ramaxeymiles is licensed under CC BY 2.0



Searches for each term separately

Searches for all terms in a single article

Expands the search

Narrows the search

More results

Fewer results

Used between synonyms

Used between concept groups

Surround each group with ( )

No special punctuation


For Example:

(stroke OR brain infarction OR ischemia)


(paralysis OR paralyze OR paralyzed)

If we insert more terms in each OR grouping, we will get more results.

If we add another concept, like a specific age group, we will get fewer results.

Some databases allow for more complicated searches with multiple terms.  Other databases do not.  It is helpful to know what the database you are using will allow.