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PubMed Research Guide: Sample Searches

This guide will help you learn how to use PubMed.

Sample search topic: depression in cancer

In this walk-through tutorial, we will cover how to use PubMed to find articles on the sample topic “depression in cancer.” Complete the steps described along with this guide to practice using PubMed.

Please note: PubMed is updated constantly, so don’t worry if your results don’t match the ones in the images exactly.

Simple keyword searches in PubMed

Simple keyword searches in PubMed:

PubMed can be used for quick Google-like keyword searches, which you can do from the homepage.

The good news: it’s a fast way to access scholarly articles on a topic.

The bad news: (1) with over 22 million citations in PubMed, you are likely to retrieve too many results, many of which may be irrelevant and (2) because of differences in terminology use, you may miss a lot of relevant results too.

For best results, always start your searches with the Medical Subject Headings (MeSH).

Medical subject headings (Mesh)

Many databases, including PubMed, allow you to use subjects as well as keywords. What is the difference?

Keywords are the words we tend to use in daily life: "heart attack," "cancer," etc. They are what you enter when doing simple searches in PubMed. However, when you search for a keyword, you are depending on the authors of an article using the same keywords you did. If so, your keywords will match the words used in the article's title, abstract, etc. and it will show up in your search results.

Subjects are the field's professional terms: "myocardial infarction," "neoplasms," etc. Subjects are assigned to each citation by indexers to ensure your searches catch all articles on a topic even if the authors did not use the same keywords you did. For example, if you search for "lung cancer" but the author used the phrase "pulmonary neoplasms" instead, you may not find that article with keywords, but you will find it if you search for the subject "lung neoplasms."

PubMed's subjects are called MeSH terms. Each citation included in PubMed is reviewed by an indexer and assigned MeSH terms that describe it to ensure your searches catch all articles on a topic even if different authors use different words for the same concept (such as cancer vs. neoplasm vs. tumor). Although PubMed automatically maps keywords to subjects, to ensure only the subjects you want are used, use the MeSH database to select the subjects yourself.

Access the MeSH database from the “More Resources” column on the homepage.

To use the MeSH database, type a keyword in the text box at the top of the page and click “Search.”

Medical subject headings (Mesh) (Cont.)

You will get a list of MeSH terms in the results page with a brief definition of each. Click on a term to see its entry. In this case, we will click on “Neoplasms."

MeSH entries include a full definition of the term, a list of subheadings, and more. Read the definition to make sure this is the term you want, then check any subheadings that interest you. If you want to include all the subheadings in your search, don’t check any of the boxes.

Below the subheadings you will see an option that says “Restrict to MeSH Major Topic.” Check this box only if you want this particular MeSH term to be the major focus of an article.

For this sample search, we will choose the “psychology” subheading but leave the “Restrict to MeSH Major Topic” box blank.

Once you have checked any boxes you want to use, click the “Add to search builder” button on the left to add the MeSH term to your search.

Repeat the process for every keyword you want to include in your search. Go ahead and try it again now for the keyword “depression.” Notice PubMed includes two MeSH terms for depression: (1) "Depression" for an affective state and (2) "Depressive Disorder" for the affective disorder. For our sample search, we will use the MeSH term "Depression."

Once you have added all MeSH terms to your search, the complete search phrase will appear on the left in the box titled “PubMed search builder.”

By default, PubMed will place an “AND” between your MeSH terms, but you can change to a different Boolean operator by clicking on the drop-down menu below the search builder box before adding a MeSH term to the search phrase.

Before running the search, always double-check the search phrase to make sure everything is correct and don’t forget to add/edit parentheses as needed to keep related concepts together. Once you click “Search PubMed,” you will be taken directly to the PubMed database and will have to go back to the home page if you want to search for more MeSH terms.

Ready? Click “Search PubMed.