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Tips and Tricks for Health Sciences Databases

Information on how to search health sciences databases using Boolean operators, quotation marks, asterisks, and more.

Searching Databases: Basic Steps

  1. Break your research topic into keywords. (Tip: many databases use specific terms, such as MeSH terms or CINAHL Headings, to label documents. Look at the "official" database terms to improve your search terms.)
  2. Combine your keywords/search terms with Boolean operators (AND, OR, NOT).
  3. Use parentheses, quotations marks, and/or asterisks with your terms and Boolean operators to create your search phrase.
  4. Determine your conditions (such as publication year or document type) and apply them to your search as limits or filters.

Boolean Operators (AND, OR, NOT) to Combine Terms

Use Boolean operators (the words AND, OR, and NOT) to combine your search terms.

  • Use AND when you want to include all of two or more terms together in the same search – use with independent concepts. AND will limit your results with each additional term.
  • Use OR when you want to include any of two or more terms in a search – use with related concepts. OR will expand your results with each additional term.
  • Use NOT when you want to exclude a term from your search. NOT will limit your results and is useful to avoid retrieving irrelevant items, but use NOT with caution! By excluding an item that briefly mentions the unwanted term, you might be excluding an otherwise useful resource.

You can use as many Boolean operators as you like in a search phrase, but include related concepts in parentheses to keep the phrase organized (this is called nesting). For example:

  • Dog OR Canine AND Bark NOT Tree: Messy
  • (Dog OR Canine) AND (Bark NOT Tree): Clear

For more information and additional examples, view the Video Tutorials on this guide.

Quotation Marks to Keep Words in Phrases Together

Use quotation marks (“ ”) around phrases to keep words together. For example, a search for tumor marker in PubMed will retrieve both of the articles below. A search for “tumor marker” will retrieve only the second article.

  • Article 1: [A]ngiogenesis is a major prerequisite for tumor growth…. In addition, the cells presented with a significantly increased expression of the apoptosis marker.
  • Article 2: The tumor marker levels decreased temporarily, but increased again 12 months after surgery...

Note: in some databases, you cannot use quotations marks and asterisks together. See the box below, "Asterisks to 'Fill-in-the-Blank,'" for examples.

Asterisks to "Fill-in-the-Blank"

Use asterisks (*) to “fill-in-the-blank” at the end of a word (this is called truncation). The asterisk will be replaced by any applicable letters. (You can use asterisks as a shortcut for OR-ing words that have identical roots.)

For example, therap* will search for therapy, therapies, therapist, therapists, therapeutic, etc.

Be careful where you place the asterisk. A search for car* as a “shortcut” for cardiac, cardiology, etc. will also retrieve items on carcinogenesis, car safety, and Caraboose the tooth fairy moose.

Note: in some databases, you cannot use quotations marks and asterisks together. For example:

  • "Group Therap*": Will Not Work in All Databases
    • Accepted in: Cochrane Library, EBSCO databases such as CINAHL, Ovid databases such as MEDLINE, ProQuest databases such as MEDLINE, Web of Science
    • Not Accepted in: Embase, PubMed
  • Group AND Therap*: Ok in All
  • "Group Therapy" OR "Group Therapist": Ok in All

Additional Tips and Tricks

Tying It All Together: Example Search

Let’s say you are conducting a search in Imaginary Health Database on the role of antioxidants in heart disease.

Note: don't be alarmed by the length of the search phrases below. Because this is an all-inclusive example, the final search phrase is much more complex than you will normally use in your research.

Attempt 1 AND: Identify your keywords and combine them with AND.


  • Antioxidants
  • Heart Disease

Since you want articles about both of these topics, use AND in your search. You can use truncation (*) to search for both the singular and plural forms of a keyword.

Antioxidant* AND "Heart Disease"
10 results in Imaginary Health Database

You want more than just 10 results, so you decide to add a few terms and see if they will help you retrieve more citations.

Attempt 2 - AND + ORIdentify related keywords and add them with OR.

Keywords (related):

  • Antioxidants:
    • Vitamin A
    • Vitamin C
  • Heart Disease:
    • Cardiac Disease
    • Cardiomyopathy

Since you would be happy with articles about any of these topics, now you can start using OR in your search. Use parentheses to keep the related keywords together.

(Antioxidant* OR "Vitamin A" OR "Vitamin C") AND ("Heart Disease" OR "Cardiac Disease" OR Cardiomyopathy)
50 results in Imaginary Health Database

Now you have many results, but you notice a lot of them are about diabetes, which you don’t want.

Attempt 3 - AND + OR + NOT: Identify unwanted keywords and add them with NOT.

Keywords (unwanted):

  • Diabetes
  • Hyperglycemia

Time to use NOT for those unwanted terms (and, yes, you can use double or even triple parentheses to keep things neat):

((Antioxidant* OR "Vitamin A" OR "Vitamin C") AND ("Heart Disease" OR "Cardiac Disease" OR Cardiomyopathy)) NOT (Diabetes OR Hyperglycemia)
30 results in Imaginary Health Database

Just right! Your final search phrase looks like this: