Searching the PubMed database
What is PubMed?
• Freely available bibliographic database produced by US National Library of Medicine (NLM) and the
National Center for Biotechnology Information (NCBI)
• Indexes over 4,900 journals in the fields of medicine, nursing, dentistry, veterinary medicine, health care
systems and the pre-clinical sciences
• Covers over 18 million citations from 1950 to date
• Updated daily
• Covers various types of journal article including review articles, randomised controlled trials, systematic
reviews, case studies and correspondence
• Does not cover books, conference proceedings or government reports
• Results are usually returned as citations and abstracts. There are a small number of connections to free full
text from PubMed, notably through PubMed Central.
• Freely available at http://www.pubmed.gov.
Text word searching (putting it straight in the search box)
• Your search words can be a keyword or phrase, or an author's name.
• Author searching: Enter the name in the format surname then initial(s) (no punctuation),
e.g. greenhlagh t. PubMed will automatically look for authors who also have a second initial.
• Keyword or phrase searching: Note that your term will be searched in exactly the form in which you enter
it – think of it as a pattern of letters. For a thorough search you will need to think of all the possible ways in
which an author might have expressed a particular concept. Give particular thought to the following:
Synonyms such as: stroke/CVA/cerebral vascular accident
Variant spellings such as: foetus/fetus (remember different American usage) where you will need to
enter both variants
Plural and adjectival forms such as: hormone/hormones/hormonal where you will need to enter all
possible forms or use the truncation symbol ( *); hormon* will retrieve all words beginning with this root
Broader/narrower concepts: think of broader and more specialist terms such as: antibiotic*/penicillin*
• You can enter one or more terms e.g., vitamin c common cold and behind the scenes PubMed will
automatically try to search for an appropriate subject heading as well as the pattern of letters. Click on
details to see exactly what search has been done.
• Phrase searching: This is done by entering the phrase in quotes, e.g. "single cell".
Subject searching – Using MeSH terms
• All records in the MEDLINE database are indexed with standard terms known as MeSH (Medical Subject
Headings – the MEDLINE ‘Thesaurus’). These provide a consistent way to retrieve information where
different terminology may be used for the same concept.
• First, click on MeSH database on the left of the screen, enter a term and click on Go. This will give you a
list of suggested MeSH terms with definitions.
• Click on the term you are interested in. A list of subheadings and associated terms will be displayed. Tick
the main heading if you want to keep the search broad. Choose one or more subheadings if you want to
narrow the search down.
• You can choose to Restrict Search to Major Topic headings only. This will only give you references where
your chosen heading is the main subject in the article.
• You can exclude narrower terms from your search by ticking the box next to “Do Not Explode this term”.
• When you have made your choices, click on links (right hand side of the screen) and then PubMed. Your
search will then run.
• Repeat the above procedure with different concepts to build up a more complex search.
Combining and refining your search
• Click on History to view a list of the searches you have done. Note each search has a number ie #1, #2
• Two or more searches can be linked using the Boolean operators, AND, OR, NOT (not case-sensitive). Be
careful when using NOT as this can eliminate useful references.
vitamin c OR ascorbic acid retrieves records that contain either “vitamin c” or “ascorbic acid” or both
back pain AND physiotherapy retrieves records that contain both “back pain” and “physiotherapy”
asthma NOT children retrieves records that contain “asthma” but not “children”
• To combine previous searches, click on the History tab then enter the search statement numbers separated
by OR or AND, e.g: #2 OR #5; #3 AND #4
TIP: Very recent records on PubMed may not have been indexed yet, and a MeSH search alone will therefore
fail to pick them up. Avoid this by combining a text word and MeSH search on the same concept using OR.
Limiting your search
• If you find that you have too many references, one option is to limit your results – click on the Limits tab to
see the options.
• You can limit by field (e.g. title, abstract), publication type (e.g. editorial, letter or review), language (note
that many non-English articles have English language abstracts), dates or date ranges, age, gender, etc.
• If you have chosen limits, the box next to Limits will be ticked and a listing of your limit selections will be
TIP: Limits will apply to all subsequent searches unless you uncheck the Limits tab.
Viewing records on PubMed
• The default display for results is Summary. This includes the author/s, title, journal name, and language (if
the full text of the article is not in English).
• Click on the hyperlinked author names to see an abstract (if available).
• The Related Articles link on the right-hand side will give you a list of articles that are similar to the one
Marking, printing and saving records
• You can ‘mark’ records of interest by checking the tick-box next to the record.
• Select how you want your results displayed by using the Display pull-down menu to select the desired
format. What you have on screen is what will be saved / printed / e-mailed.
• Select where you want to send the records by clicking next to ‘Send to’ in the grey tool bar.
Send to text to create a text file
Send to file to save to your hard drive, filestore, floppy or USB drive
Send to clipboard to save records temporarily (they will be kept as long as you do not close the
browser window, for a maximum of 8 hours). View your saved records by clicking on the Clipboard tab.
Send to email if you want to email your results.
• To print your search results, mark the citations you want to print, use the pull-down menu to select the
desired format and then click send to Text. Use your Web browser print options to print your results.
Saving the work you have done
• To save the work you have done you must first register with MY NCBI (top right of screen).
• You will need to provide a username and password.
• Once you are registered you can save your searches: go to history and click on the search number you
wish to save ie #8. Choose the option save in my NCBI.
• Give your search a name that you will remember!
• You will also be given the option of setting up e-mail alerts for new articles that fir your search.
• For on-screen help click on Help|FAQ on the blue menu bar at the side of the screen.
• Work through the PubMed tutorials on this menu.
RP October 2008, with acknowledgements to Ruth Murphy, UCL