Skip to Main Content

PubMed @ UMSL

Step-by-step guide to PubMed's basic and advanced features, with downloadable handouts.

Simple Keyword Searching

Basic search for "blood draw babies"

PubMed’s search interface is about as simple as they come. Simply type your keywords into the search bar and click Search. The challenge is then narrowing or expanding your search and understanding how PubMed interprets your search to find results.

When you run a simple search, as shown in the image above, PubMed attempts to translate your keywords into standard vocabulary (MeSH terms), using a process called automatic term mapping (ATM). For instance, a search for blood draw will find results that include either blood draw or its corresponding MeSH term blood specimen collection; a search for babies will find results that include either babies or the MeSH term infant.

To see how PubMed is interpreting your search query, see the Search Details area of the History section on the Advanced Search window. For more on the Search Details box, see Displaying and Sorting Results.

Truncation and Phrase Searching

You can truncate keywords by typing an asterisk (*) in place of one or more letters to simultaneously search for different forms of a word. For example, isolat* will search for isolate, isolated, isolating, isolation, etc., and bull* will search for bully, bullies, bullyingbullbulls, bullfighting, etc.

You can also employ phrase searching by enclosing words in double quotation marks (“ ”) to search for an exact phrase. So a search for “post-traumatic stress disorder” will find references that contain that exact phrase but will overlook references that use the phrase post-traumatic stress syndrome instead.

 WARNING  Truncation and phrase searching are perfectly valid search techniques, but they will prevent PubMed from using ATM to translate your keywords. For instance, PubMed knows to interpret mad cow disease as encephalopathy, bovine spongiform, but it doesn’t know what MeSH terms to apply to a phrase search of “mad cow disease”—so all it can do is search for the phrase and not expand it to find equally relevant results. In PubMed, it’s usually best to start with ATM (PubMed's automatic term mapping) and only use truncation and phrase searching if you’re not getting the results you want.

Boolean Operators (AND, OR, NOT)

Three Venn diagrams representing the intersection of heart AND lung, the separation of heart OR lung, and the exclusion of heart NOT lung.

In PubMed, as in many databases, the default operator is AND—so a keyword search of exercise anxiety will look for results that contain both words (and will not strictly search for articles that discuss anxiety about exercise; for that, you should consider a phrase search, as discussed in the Truncation and Phrase Searching section). 

Grouping Terms Together Using Parentheses

Parentheses can be used to control a search query. Without parentheses, a search is executed phrase by phrase, from left to right. When you enclose words in parentheses, they are searched first. Parentheses allow you to control and define the way the search will be executed.

Generalized Search: heart or lung and blood or oxygen
Focused Search: (heart or lung) and (blood or oxygen)

In the first example above, the search will retrieve a lot of results:

  1. Everything on "heart"
  2. Everything that references "lung" and "blood"
  3. Everything on "oxygen"

In the second example, the parentheses control our query: the left phrase in parentheses is searched first, and then—based on those results—the second phrase in parentheses is searched. This search will only find articles about heart or lung that reference blood or oxygen.