How to search PubMed

Subject headings are specific terms or phrases that describe the content of each item in a database. These headings are used to find relevant articles on the same topic.  Searching by subject headings is the most precise way to search article databases.

It is not easy to guess which subject headings are used in a given database. You might have to find what term is used for a subject first before using it.

PubMed has a list of standardized subject headings known as Medical Subject Headings (MeSH). Look to see if PubMed has a subject that matches your topic, and then search the database using that subject heading.

1. From PubMed main search window, click on MeSH Database.

In the MeSH database you are searching for the Subject Heading for your term so that you can add it to your search.

2. Type in the term you are looking for (e.g. mobile phone) and click Search. 
   PubMed will display the most appropriate term for you to use in your search.  In the case of the example for "mobile phone" the correct subject heading to search is "Cell Phone".  
    
3. Click on the check box beside "Cell Phone" to select the subject for searching.
    
4. Click Add to Search Builder to add this to your search.
   PubMed adds the term to the "PubMed Search Builder" window using the proper search syntax.  In this case... "Cell Phone"[Mesh] 
   
5. Now click Search PubMed to proceed with searching for this subject heading.

Each subject heading may be further refined using Subheadings.  These terms help the researcher to quickly narrow in on a specific aspect of the subject heading. 

When searching on the topic of "What is the risk of mortality due to cell phone use in distracted teen drivers?"  One of our subject headings would be "distracted driving".  We might be specifically interested in prevention and control, statistics and numerical data, and trends in distracted driving. 

Searching PubMed for subject headings and subheadings:

1. From PubMed main search window, click on MeSH Database.
2. Type in the term you are looking for (e.g. distracted driving) and click Search. 
3. Click the the title of the appropriate subject heading.
   PubMed displays the subheadings associated with the subject heading.
4. Click the check box(es) next to the subheadings of interest (e.g. prevention and control, statistics and numerical data, trends). 
5. Click Add to search builder (button).
   The selected subheadings are added to the search in the PubMed Search Builder.
   e.g. ( "Distracted Driving/prevention and control"[Mesh] OR  "Distracted Driving/statistics and numerical data"[Mesh] OR  "Distracted Driving/trends"[Mesh] )
6. Click Search PubMed (button).

PubMed MeSH can be further classified as minor and major subject headings.  These reflect the focus of the paper they are assigned to. When you look at an item record in PubMed you can see which subject headings are the major and which are the minor ones. The major subject headings are identified with an * (or asterisk). This classification can be used to further refine searches with a large number of results.

Flaherty MR, Kim AM, Salt MD, Lee LK. Distracted Driving Laws and Motor Vehicle Crash Fatalities. Pediatrics. 2020 Jun;145(6):e20193621. doi: 10.1542/peds.2019-3621. Epub 2020 May 15. PMID: 32414896. [click to see MeSH headings]

Using the example "What is the risk of mortality due to cell phone use in distracted teen drivers?".  We might decide that we want the concept of "distracted driving" to be the major concept of the papers we are interested in.

Searching for major topic in PubMed MeSH:

1. From PubMed main search window, click on MeSH Database.
2. Type in the term you are looking for (e.g. distracted driving) and click Search. 
3. Click the the title of the appropriate subject heading.
4. Click the check box next to Restrict to MeSH Major Topic.
5. Click Add to search builder (button).
   The subject heading is added to the search in the PubMed Search Builder.
   e.g. "Distracted Driving"[Majr]
6. Click Search PubMed (button).

Searches using MeSH terms can sometimes provide unintended results.  This is often due to the automatic inclusion of narrower terms found under a subject heading.

To see what terms are included with a Subject Heading:

1. From PubMed main search window, click on MeSH Database.
2. Type in the term you are looking for (e.g. cardiovascular diseases) and click Search. 
3. Click the the title of the subject heading.
   e.g. Cardiovascular Diseases - MeSH Search
4. Scroll down the mesh page for the subject heading until you see All MeSH Categories. Your term is bolded and below it is a list of all the narrower terms associated with the subject heading. You need to decide if this is helpful to your search or if it is problematic.
   1. Helpful?
      Continue with the default search by:
      1. Scroll back up to the top of the page and click Add to search builder (button).
         The subject heading is added to the PubMed Search Builder.
         e.g. "Cardiovascular Diseases"[Mesh]
      2. Click Search PubMed (button).
   2. Problematic?
      Search only the specific term of interest by:
      1. Scroll back up to the top of the page and lick in the check box next to Do not include MeSH terms found below this term in the MeSH hierarchy.
      2. Click Add to search builder (button).
         The modified subject heading is added to the PubMed Search Builder.
         e.g. "Cardiovascular Diseases"[Mesh:NoExp]
      3. Click Search PubMed (button).

If your search has too many results consider using one or more of these methods to refine your subject heading searches:

• use subheadings
• use major concept
• use Do not include MeSH terms found below this term in the MeSH hierarchy

If your search has too few results consider the following for your subject heading searches:

• select all subheadings (default)
• do not use major concept
• use explode where it's available

Librarians often start a subject heading search by using the default setting of applying all subheadings.  This is to be as inclusive as possible of results.  It is often better to allow searches to be refined by using other concepts (with boolean operators) rather than focusing on specific subheadings or major concepts.  If the final set of results is too large they will go back and do further refinement.

1. Start with a keyword search, using words/phrases that describe your topic.
2. Browse the results; choose 2 or 3 that are relevant.
3. Click on the title of the article of interest.
4. Look at the MeSH and note the terms used (write them down).
5. Redo your search using those terms.
6. Your results will be more precise than your initial keyword search.