PubMed Help PubMed Help

Searching PubMed

Section Contents

A basic search
  1. Identify the key concepts in your research question.

Example
Find citations about bronchodilators for treating asthma in children.
The key concepts are bronchodilators, asthma and children

  1. Enter the significant terms into the search box.
  2. Press the Enter key or click Go.

A spell checking feature suggests alternative spellings for PubMed search terms that may include misspellings.

A Citation Sensor displays results for searches that include terms characteristic of citation searching, e.g., author names, journal titles, and publication dates.

A Gene Sensor checks queries, and if it detects the symbol for a gene, links to the Gene database.

To modify your current search, change your search terms in the search box or in Details.top link

Searching by author

Enter the author’s name in the format of last name followed by initials. Omit punctuation.

Examples
smith ja
jones k

More information about author searching:

  • Click the Limits tab to use the author search builder that includes an autocomplete feature.
  • Author names are automatically truncated to account for varying initials and designations such as Jr. To turn off the truncation, use double quotes around the author's name with the author search field tag [au], e.g., "smith j" [au].
  • If only the author's last name is entered, tag the name search with the author search field [au], to find the name in the author field only.
  • Use the [1au] tag to search for the first personal author or [lastau] to search for the last personal author name in a citation.

Example
woods [au]

Full author names may be searched for citations published from 2002 forward if the full author name is available in the article. Enter a full author name in natural or inverted order, e.g., julia s wong or wong julia s.

Example
Joshua Lederberg
Garcia Algar, Oscar

More information about full author searching:

  • A comma following the last name for searching is optional. For some names, however, it is necessary to distinguish which name is the last name by using the comma following the last name, e.g., james, ryan.
  • Omit periods after initials and put all suffixes at the end, e.g., vollmer charles jr
  • Initials and suffixes are not required, if you include a middle initial or suffix, you will only retrieve citations for articles that were published using the middle initial or suffix.
  • To distinguish author initials that may match a full author name use the [fau] search tag, e.g., peterson do[fau].
Searching by journal title

Enter in the search box one of the following:

  • full journal title (e.g., molecular biology of the cell)
  • title abbreviation (e.g., mol biol cell)
  • ISSN number, a standardized international code (e.g., 1059-1524)

Example
new england journal of medicine

To find full journal names, use the Journals database.

  1. Click Journals Database on the PubMed sidebar.
  2. Enter the journal name and click Go.
  3. Check the Suggestions if the journal name does not display in the results.
  4. Choose PubMed under the Links menu to search for the journal.

More information about journal searching:

  • Use the Single Citation Matcher that includes a journal autocomplete feature.
  • Click the Limits tab to use the journal search builder that also includes an autocomplete feature.
  • If a journal title is also a MeSH term (e.g., Gene Therapy, Science, or Cell), PubMed will search the untagged term as MeSH. Tag the journal title by using the Journal Title search field [ta] to search for the journal (e.g., gene therapy[ta]).
  • If a journal title is a single word, tag the title using the Journal Title search field (e.g., scanning [ta]). Otherwise, PubMed will search the untagged single word journal title as a MeSH term (if applicable) or as All Fields.
  • Searching with the full journal title or title abbreviation is recommended for complete retrieval of indexed items; older citations may not have an ISSN.
  • If a journal title or title abbreviation includes a special character (e.g., parentheses, brackets, &), enter the title or abbreviation without the special characters.  For example, to search j hand surg [am], enter j hand surg am.
  • Searching for a journal will automatically map to the official journal title and the title associated with an alternative title, if one exists. To turn off this automatic mapping enclose the journal in double quotes and tag with [ta].
  • A list of all journals that are included in the PubMed database is available by FTP in the Uncompressed, GNU Zip, UNIX Compress, or PKZIP format.
Searching by date
  1. Click the Limits tab.
  2. You may limit your search to articles published or added to PubMed by a pre-set date range by choosing the date range from the Dates menus.
  3. You may also enter any desired date range by selecting Specify date range (YYYY/MM/DD) under the menus. Enter a single date or a date range in the fill-in-the-blank boxes. Month and day are optional. If you want to search for a date range up to the current date, leave the To date boxes blank.
  4. Select additional search limits or add search terms to the search box, if desired. Click Go.

When you start a new search, turn off the Date limit by clicking the Limits tab check box.

More information about date searching:

Searching by a single date in the search box

Enter dates using the format YYYY/MM/DD [date field]. There is a selection of date fields to use:

  • Date of Publication [dp]
  • Entrez Date [edat] - The date the citation first entered PubMed.
  • MeSH Date [mhda] - The date the citation was indexed with MeSH terms.

The month and day are optional.

Example
1997/10/06 [edat]
1998/03/15 [dp]
1997 [edat]
1997/03 [dp]

Searching for a date range in the search box

Enter date ranges using a colon (:) between each date followed by a [date field].

Example
1993:1995 [dp]
1997/01:1997/06 [edat]

Comprehensive searches for a full year should be entered as 2000:2000[dp] rather than 2000[dp] to retrieve citations with a different print and electronic year of publication.top link

Searching for a relative date range

Use the following format to search for a relative date range:

  • term="last X days"[Search Tag]
  • term="last X months"[Search Tag]
  • term="last X years"[Search Tag]

where X is the number of days, months or years immediately preceding today’s date and [Search Tag] is the date search tag:[dp] or [edat].top link

Limit your searches (Limits)

You can limit your search by full text or free full text, age group, gender, humans or animals studies, languages, publication types, dates, and by other parameters.

Limits also includes a search builder for authors and journals.

  1. Click the Limits tab.
  2. You may enter an author or journal.
  3. Choose any limit selections from the options available on the page.
  4. If necessary, make changes to the search terms in the search box or enter a new search.
  5. Click Go.

Note:

  • The "in process" and "supplied by publisher" citations may be excluded for some limit selections because they have not yet completed the MEDLINE indexing process and may not include these data.
  • When Limits are “in effect” a check will appear in the Limits tab and your selected limits will display in a yellow bar. To turn off limits click off the Limits tab check box and run a new search.
  • Go and Clear All Limits buttons are available at the bottom of the Limits page. The Go button function at the top and bottom of the page is equivalent.
Limit parameter details

Author and Journal

To search by author, click Add Author.

  • An author search box will display. The author search box includes an autocomplete feature; enter a name in the Author name box and you will see a list of suggested names that gets shorter as you type more letters. As soon as you see the author name you are looking for, you may select that name.
  • To add additional authors, click the Add Another Author link to open another author search box. The default author search is to include all author names in your search. To change this to search for any authors you selected click the radio button from All these authors to Any of these. Click the remove link to delete an author search box.
  • Author names will automatically move to the PubMed search box when you click Go.
  • Selected limits will be activated for any subsequent searches except for authors and journals. Author and journal selections will only be included in subsequent searches if they are not cleared from the PubMed search box.

To search by journal, click Add Journal.

  • The journal search box also includes an autocomplete feature; enter a name in the journal name box and you will see a list of suggested names that gets shorter as you type more letters. As soon as you see the journal title you are looking for, you may select it.
  • To add additional journals, click the Add Another Journal link to open another journal search box.
  • Search results will include any of the selected journals.
  • Journals will automatically move to the PubMed search box when you click Go. Author and journal selections will only be included in subsequent searches if they are not cleared from the PubMed search box.
Full Text, Free Full Text, and Abstracts

To limit your search results to only citations that include a link to full text, a link to free full text, or an abstract, click the appropriate check boxes.

Alternatively, you may search for citations with links to full text, free full text or include an abstract using the values: full text[sb], free full text[sb], or 'hasabstract'. No search field tag is required for hasabstract.

Example
neoplasms AND hasabstract

Note: Most citations in PubMed to articles published before 1975 do not include abstracts.top link

Published or Added to PubMed Dates

You may limit your search to articles published or added to PubMed by a pre-set date range, e.g., in the last 60 days; or you may enter any desired date range by selecting Specify date range (YYYY/MM/DD) from the Dates menus.

If you select Specify date range from a date Dates menu, enter a single date or a date range in the fill-in-the-blank boxes. Month and day are optional. If you want to search for a date range up to the current date, leave the To date boxes blank.

PubMed displays search results when the citation was added in descending order, i.e., last in, first out.top link

Humans or Animals

The Humans or Animals limit restricts your search to a human or animal study.

With this limit, PubMed retrieval will be limited to MEDLINE citations. The "in process" and "supplied by publisher" citations will be excluded because they have not yet completed the indexing process and do not carry these data.top link

Gender

The gender limit restricts your search to a specific gender for a human study.

With this limit, PubMed retrieval will be limited to MEDLINE citations. The "in process" and "supplied by publisher" citations will be excluded because they have not yet completed the indexing process and do not carry these data.top link

Languages

The languages limit restricts your search to articles written in a particular language.

Languages initially displays a list of the most frequently used languages:

  • English
  • French
  • German
  • Italian
  • Japanese
  • Russian
  • Spanish

The complete list of languages is available under the More Languages label.top link

Subsets

Journal Groups & More Subsets

The Journal/Citation subsets restrict retrieval to specialized journals or articles on specialized topics in other journals. The table lists the Journal subsets, along with the value used for searching. (Note: some subsets are closed and no longer being assigned to current data.)

To search for a Journal/Citation subset, enter in the search box: jsubset?, where ? represents the subset value.

Example
neoplasms AND jsubsete
This search will limit retrieval to citations from bioethics journals or selected bioethics citations from other journals.

The Journal/Citation subset does not require a search tag.top link

Topics

The topics subsets restrict retrieval to specific subjects including:

  • AIDS
  • Bioethics
  • Cancer
  • Complementary Medicine
  • History of Medicine
  • Space Life Sciences
  • Systematic Reviews
  • Toxicology

Each topic subset limit uses its own specialized search strategy.

Alternatively, each topic subset can be searched using the respective search value of aids, bioethics, cancer, cam, history, space, systematic or tox followed by the [sb] search tag.

Example
asthma AND cam [sb]

Do not confuse the topic subsets for AIDS, Bioethics, Cancer, History of Medicine, and Space Life Sciences with the journal or other subsets (see below) for the same topics, i.e., jsubsetx, jsubsete, jsubsetq, and jsubsets.top link

PubMed Central Subset

This subset restricts retrieval to citations that have a full-text article available for free in PubMed Central (PMC).

To search for PubMed Central citations use Limits Subsets, or simply enter pubmed pmc local[sb] into the search box.

Example
protein p53 AND pubmed pmc local[sb]

To search for all citations that have free full-text articles available (both PMC citations and citations where the free full-text article is provided directly from the journal’s Web site in PMC), enter pubmed pmc[sb] in the search box.

Use the PMID : PMCID Converter to translate one type of ID to the other.top link

Citation Status Subsets

The citation status indicates the processing stage of an article in the PubMed database (see PubMed Citation Status Subsets).

The status tags are displayed with each citation in the search results. To search for a particular citation status, enter one of the search terms below followed by the [sb] search tag

  • publisher
  • in process
  • medline
  • oldmedline
  • pubmednotmedline

Example
n engl j med AND medline [sb]

To search for the total number of PubMed citations, enter all [sb] in the search box.

Note: The MEDLINE subset can be selected from More Subsets in Limits.

For additional information, see PubMed's Overview.top link

Ahead of Print Citations

Publishers may submit citations for articles that appear on the Web in advance of the journal issue's release. These are ahead-of-print citations.

To search for ahead of print citations, enter pubstatusaheadofprint into the search box

Example
pubstatusaheadofprint AND gene

Following publication of the completed issue, the date an article was published electronically is retained on these citations, e.g. Proc Natl Acad Sci U S A. 2003 Apr 1;100(7):3925-9. Epub 2003 Mar 24.top link

Publication Types

The publication type limit will restrict your search based on the type of material the article represents, such as:

  • Clinical Trial
  • Editorial
  • Letter
  • Meta-Analysis
  • Practice Guideline
  • Randomized Controlled Trial
  • Review

The complete list of publication types is available under the Limits Type of Article More Publication Types.

With this limit, PubMed retrieval will be limited to MEDLINE citations. The "in process" and "supplied by publisher" citations will be excluded because they have not yet completed the indexing process and will not include a Publication Type.top link

Ages

The Limits age groups restrict your search to a specific age group for a human study, and include:

  • All Infant: birth-23 months
  • All Child: 0-18 years
  • All Adult:19+ years
  • Newborn: birth-1 month
  • Infant: 1-23 months
  • Preschool Child: 2-5 years
  • Child: 6-12 years
  • Adolescent: 13-18 years
  • Adult: 19-44 years
  • Middle Aged: 45-64 years
  • Middle Aged + Aged: 45+ years
  • Aged: 65+ years
  • 80 and over: 80+ years

With this limit, PubMed retrieval will be limited to MEDLINE citations. The "in process" and "supplied by publisher" citations will be excluded because they have not yet completed the indexing process and do not carry these data.top link

Tag Terms

To limit untagged search terms to a specific citation field choose a field from the Tag Terms All Fields menu located at the bottom of the Limits page.

See Also: Searching in a specific field of indextop link

Searching for a phrase

PubMed does not perform adjacency searching. However, many phrases are recognized by the MeSH Translation Table used in PubMed's Automatic Term Mapping (ATM) feature. For example, if you enter fever of unknown origin, PubMed recognizes this phrase as a MeSH concept. If a phrase is not recognized you can instruct PubMed to bypass ATM and search for a phrase using the formats outlined below.

Examples
  • Enclose the phrase in double quotes: “kidney allograft”
  • Use a search tag: kidney allograft[tw]
  • Use a hyphen: first-line
  • Truncate: kidney allograft*

More information for phrase searching:

  • If you use a hyphen or quotes and the phrase is not found, the hyphen or quotes are ignored and the phrase is processed using automatic term mapping. Phrases may appear in a PubMed record but not be in the phrases index.
  • When you enter your search terms as a phrase PubMed will not perform automatic term mapping that includes explosion of MeSH terms. For example, "health planning" will include citations that are indexed to the MeSH term, Health Planning, but will not include the more specific terms, e.g., Health Care Rationing, Health Care Reform, Health Plan Implementation, etc., that are included with the automatic MeSH mapping.
  • Truncating a word in a multi-word search may result in an unexpected phrase search. For example the search, fetus infection* maternal will treat fetus infection* as a phrase. Check Details to see the search translation.
Truncating search terms

To search for all terms that begin with a word, enter the word followed by an asterisk (*).

Example
flavor*
Finds terms that begin with the root term flavor, such as flavored, flavorful, flavoring, etc.

More information about truncation:

  • PubMed searches for the first 600 variations of a truncated term. If a truncated term (e.g., tox*) produces more than 600 variations, PubMed displays a warning message to lengthen the root word to search for all endings.
  • Truncation turns off automatic term mapping and the automatic explosion of a MeSH term. For example, heart attack* will not map to the MeSH term Myocardial Infarction or include any of the more specific terms, e.g., Myocardial Stunning; Shock, Cardiogenic.
  • Truncating a word in a multi-word search may result in an unexpected phrase search. For example the search, fetus infection* maternal will treat fetus infection* as a phrase.
Combining searches (History)

Previous searches can be combined or used in subsequent searches using the search statement number from History.

  1. Click the History tab.
  2. Click on the linked search statement number to display the options menu that includes Boolean operators to AND, OR or NOT your search to the search box. Alternatively you can enter a number sign followed by the search number, e.g., #1, in the search box.
  3. Add additional search terms into the search box or combine with other searches.
  4. Click Go.

Examples
#2 AND #6
#3 AND (drug therapy OR diet therapy)
#5 gene therapy

For additional information, see Viewing your search history. top link

Finding a citation using the Single Citation Matcher

The Single Citation Matcher has a fill-in-the-blank form for searching for a citation when you have some bibliographic information, e.g., journal name, volume, page number.

  1. Click Single Citation Matcher on the PubMed sidebar.
  2. Enter the bibliographic information you have.
  3. Click Go.

More information about using the Single Citation Matcher:

  • The journal box includes an autocomplete feature that suggests titles as you enter a title abbreviation or full title. Titles displayed by the autocomplete menu are in ranked order based on the number of citations in PubMed.
  • After selecting a journal with special characters (e.g., ampersand, colon) when using the Back button to return to the Single Citation Matcher you must clear and reenter the title.
  • The author box also includes an autocomplete feature that suggests author names in ranked order based on the number of citations. Full author names may be searched for citations published from 2002 forward if the full author name is available in the article.
  • Click either the 'Only as first author' or ‘Only as last author’ check box to limit an author name to the first or last author.
Browsing PubMed's index of terms (Preview/Index)

Preview/Index provides an alphabetical display of all search terms in each PubMed search field. You can browse by all fields or within a specific field such as MeSH Terms.

  1. Click the Preview/Index tab.
  2. Select a search field from the All Fields menu at the bottom of the page.
  3. Enter a search term in the search box. If you want to see a list of all terms, leave the search box empty.
  4. Click Index.
  5. PubMed displays an alphabetic list of search terms. The number of citations for that term appears in parentheses to the right of the term. Click Up or Down to move within the Index.
  6. Select a term.  To select multiple terms (and OR them together), select on each term while holding down the Ctrl key (PC) or the Command key (Mac).
  7. Click the appropriate Boolean operator to add the search term to the search box. Be sure to clear the search box before beginning a new search.
  8. Continue adding terms (repeating steps 2 to 7), if desired.
  9. Click Go. If you only want to preview the number of results, click Preview.

More information about using the index:

  • Preview/Index displays the last three searches from History.  History retains the last 100 searches.
  • PubMed processes all Boolean operators left to right. To change this order, enclose search terms to be processed first in parentheses, e.g., common cold AND (vitamin c OR zinc). PubMed will automatically OR (and add parentheses) for multiple terms selected from the Index.
Combining search terms with Boolean operators (AND, OR, NOT)

PubMed assumes the AND operator between concepts, e.g., “vitamin c common cold” is translated as vitamin c AND common cold. Enter Boolean operators in uppercase characters to combine or exclude search terms:

  • AND retrieves results that include all the search terms.
  • OR retrieves results that include at least one of the search terms.
  • NOT excludes the retrieval of terms from your search.

Examples
Find citations on DNA that were authored by Dr. Crick in 1993:
dna [mh] AND crick [au] AND 1993 [dp]
Find articles on the effects of heat or humidity on multiple sclerosis:
(heat OR humidity) AND multiple sclerosis
Find citations about arthritis excluding the Publication Type Letter:
arthritis NOT letter [pt]

PubMed processes searches in a left-to-right sequence. Use parentheses to “nest” concepts that should be processed as a unit and then incorporated into the overall search.

Example
common cold AND (vitamin c OR zinc)

More information about using Boolean operators:

Boolean operators must be used when combining tagged search terms as follows: search term [tag] BOOLEAN OPERATOR search term [tag]. (See Search Field Descriptions and Tags)

  • In a multi-word search PubMed will use Automatic Term Mapping to identify concepts. For example, for the search air bladder fistula, PubMed will search "air bladder" as a phrase. If you do not want this automatic phrase parsing, enter each term separated by the Boolean operator AND, e.g., air AND bladder AND fistula.
  • Click Details to see how PubMed translated your search strategy.
Searching in a specific field or index

To search a specific field in a citation (e.g., author, title, journal, etc.) and bypass the automatic term mapping, tag the search term by adding the appropriate search tag (Search Field Descriptions and Tags).

  • The search tag must be enclosed in square brackets.
  • Case and spacing do not matter (e.g., crabs [mh] = Crabs[mh])

Example
aromatherapy [mh]

Previewing the number of search results (Preview)

To preview the number of citations before displaying the search results:

  1. Click the Preview/Index tab.
  2. Enter your search term(s) in the search box.
  3. Click Preview.  The number of results is displayed.
  4. To display the citations, click the result link.

Use Preview to add search terms incrementally to refine your search before retrieving the citations.

  1. Enter a search term in the search box.
  2. Click Preview.  The number of results is displayed.
  3. Continue adding terms and selecting Preview until your search is complete.

Note: Preview displays the last three searches from History.  History retains the last 100 searches.top link

Finding articles related to a citation

Click the Related Articles link on the right side of a citation.

The Related Articles link will retrieve a pre-calculated set of PubMed citations that are closely related to the selected article. The related articles will be displayed in ranked order from most to least relevant, with the “linked from” citation displayed first.

More information about Related Articles:

  • The AbstractPlus display automatically includes the first 5 Related Article citations.
  • Each citation in PubMed includes a link that retrieves a pre-calculated set of citations that are closely related to the selected article. PubMed creates this set by comparing words from the title, abstract, and MeSH terms using a word-weighted algorithm.
  • If you select Related Articles from the Display menu without selecting specific citations, PubMed will retrieve the related articles for the citations displayed on the page.
  • Limits are NOT in effect when you use a Related Articles link. After linking on Related Articles, although the box next to Limits may be checked, there is no yellow bar displaying the Limits in effect.
  • You can, however, refine the list of Related Articles using PubMed’s History feature. In History, you will see that the Related Articles retrieval is represented as "Link to PubMed from (PMID of document)." Use this Search number in a search. (Keep in mind that the list you get with a Related Articles link is displayed in ranked order from most to least relevant. Refining the list removes the ranked order and may remove citations that are most relevant.)
  • Use the ELink utility to retrieve related articles for large sets of citations.
Using Clinical Queries

The PubMed Clinical Queries page provides specialized PubMed searches for clinicians:

  • Search by Clinical Study Category
  • Finding Systematic Reviews
  • Medical Genetics Searches
Search by clinical study category

The Clinical Study Category is a specialized search method with built-in search filters that limit retrieval to citations to articles reporting research conducted with specific methodologies, including those that report applied clinical research.

To find citations using the Clinical Study Category:

  1. Click Clinical Queries from the PubMed sidebar
  2. Click Search by Clinical Study Category
  3. Enter your search term in the search box
  4. Select a Category: therapy, diagnosis, etiology, or prognosis
  5. Select a Scope: “narrow, specific search or broad, sensitive search
  6. Click Go

Example
Find research on diagnosing cystic fibrosis.
On the Clinical Queries page click Search by Clinical Study Category.
Enter cystic fibrosis in the search box.
Click “diagnosis” under Category and “narrow, specific search” under Scope, click Go.

Finding systematic reviews

In PubMed, Systematic Reviews cover a broad set of articles that build consensus on biomedical topics. This feature is provided to help clinicians locate systematic reviews and similar articles.

To find Systematic Reviews:

  1. Click Clinical Queries from the PubMed sidebar
  2. Click Find Systematic Review
  3. Enter your search terms in the search box
  4. Click Go

Example
Find Systematic Reviews on inhalation therapy for pneumonia.
On the Clinical Queries page click Find Systematic Reviews.
Enter the search terms inhalation therapy pneumonia into the search box, click Go.

Alternatively, enter search terms followed by AND systematic[sb] into the search box. For example, lyme disease AND systematic[sb].top link

Medical genetics searches

In PubMed, Medical Genetics Searches finds citations related to various topics in medical genetics.

  1. Click Clinical Queries from the PubMed Sidebar
  2. Select Medical Genetics Searches
  3. Enter search terms in the search box
  4. Change the search categories, if applicable
  5. Click Go.

Example
Find information on genetic counseling for sickle cell anemia.
On the Clinical Queries page, click Medical Genetic Searches.
Enter the search terms sickle cell anemia into the search box.
Under Category, click on All to deselect all the categories, click Genetic Counseling, click Go.

More information about Clinical Queries:

  • The Clinical Study Category search filters are based on the work of Haynes RB et al. See the filter table for details.
  • Systematic Reviews uses a customized search strategy. A list of related sources on this topic is provided.
  • In PubMed, systematic reviews cover a broad set of articles that build consensus on biomedical topics and include:
    • systematic reviews
    • meta-analyses
    • reviews of clinical trials
    • evidence-based medicine
    • consensus development conferences
    • guidelines
    • citations from journals specializing in clinical review studies
  • The Medical Genetics Searches were developed in conjunction with the staff of GeneReviews: Genetic Disease Online Reviews at GeneTests, University of Washington, Seattle. The Medical Genetic Searches use built-in search filters.

The results of these searches can be refined using PubMed’s Limits (e.g., English language). top link


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