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PubMed: Keyword search

Selecting search terms

  • When you do a key word search in PubMed, the database looks for your search terms across the titles and abstracts/summaries of articles and other documents. Think carefully about your search terms before entering them. Look at your assignment title/research question and identify its most important words or phrases (i.e. those that distinguish it from any other title/question). Generally, it's best to ignore generic words such as 'impact' or 'process'.
  • Search example: “Investigate the impact of carbohydrate drinks on endurance". The most important words/phrases are carbohydrate drink and endurance
  • For each word/phrase: think about any potential alternative words that have the same/similar meaning e.g. consider terminology used in literature, lectures and tutorials. Also consider words that mean the opposite (e.g. fatigue as well as endure). Different authors can use different words to describe the same concept and if your search terms don't reflect this, you may miss important search results.  
  • Consider whether the overall theme of your topic can be divided into separate sub-themes - if so, consider your search terms for each sub-theme separately as follows:

Sub-theme 1: carbohydate

Sub-theme 2: drink



Sub-theme 3: endurance 



Entering search terms

Click the Advanced link just below the search box on PubMed's 'homepage' to take you to the advanced search page.

  • Enter search terms using OR: If you have identified alternative search terms for a specific sub-theme within the overall theme of your assignment/research, enter the word or in between each search term e.g. NSAID or ibuprofen or naproxen or aspirin. This will potentially increase the number of your search results.

    PubMed: Keyword searching Part 1.

  • Use of AND: if your assignment title/research question has multiple sub-themes, you should enter each corresponding set of search terms separately into the search box (i.e. one set at a time).  After entering each set, click the 'Add with AND' button.  Your accumulating search terms appear in a 'query' box'.  Using the AND option means that each of your search results will include at least one search term from each set of terms that you entered.

    PubMed: Keyword searching Part 2.

  • ​Once you have entered all of your search terms, click Search to get your results.

  • Too many irrelevant results? Take another look at your keywords and see if you need to make these more precise. Perhaps an additional theme needs to appear in each result? If so, add the associated search term(s) as a separate set (again, combining these with your other set of search terms with AND).  Take a look at the terminology in titles and abstracts to help inform any changes you make.

    You could also consider changing the search box's setting from 'all fields' to 'Text word'. This will instruct PubMed to only search titles, abstracts, subject headings, substance names and a few other fields in PubMed records.


Entering truncated words and phrases

  • Truncation: with some searches, you can increase the number of your results by truncating a word and entering an asterisk at the end of its stem e.g. if you enter fractur*PubMed will search for fracture, fractures, fractured, fracturing.  

    However, with some searches, using an an asterisk can reduce the number of results! This is because PubMed records include 'subject headings' that are words/phrases drawn from a thesaurus, and your search will find any subject headings, in addition to any additional words/phrases that the thesaurus identifies as having a similar meaning. However, If your search terms include asterisks, PubMed isn't able to search for those additional words.

    The solution? You could enter your search terms twice, once with an asterisk and once without (in singular form) e.g. fractur* or fracture.