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Integrated sessions: Combine key terms - health


"When possible, avoid using the operator NOT because it tends to exclude documents you could actually use"

Lawrence A. Machi & Brenda T. McEvoy, The literature review: six steps to success

After you have identified your search terms, you need to combine your terms with the aid of Boolean operators. Boolean consists of connectors that combine your search terms. Let’s take a look at the Boolean operators to know how it helps us to get appropriate results.

The boolean operators below demonstrate examples for the question: “Discuss the impact of high blood pressure in teenagers.”


AND operator

Use AND to combine and find information on all of your search terms. This will narrow your search. When using AND, you only receive pages including both of your search terms, though not necessarily next to each other. You can search for 'high blood pressure AND teenagers' to get results including high blood pressure related to teenagers.


OR operator

This shows a venn diagram that demonstrates the use of the OR operator to link teenagers and teens. It finds content that contain both teens, teenagers or both

Use OR to look for alternative terms, phrases or synonyms to broaden your search. When using OR, you receive pages containing either one or both of your search terms. Searching for ‘teenagers OR adolescents’ will get results including either term or both.


NOT operator

This shows a venn diagram that demonstrates the use of the OR operator to link teenagers and NOT pre-teens. It only finds content that contains teenagers alone. If content also included pre-teens it would be excluded

Use NOT to exclude a specific term from your search which will again narrow your search. The NOT operator is used to find pages including only the first term and excluding the second term. You can search for ‘Teenagers NOT Adults’ to get results specific to teenagers only and not get any results related to adults.

Be very careful in your use of this operator - it can exclude relevant material. For example, an article might discuss 'young adults' but it would be excluded as it contains the term 'adults'.



You can use parentheses to group the logic of different boolean operators. It allows you to group similar terms and separate your key search terms.


See the following examples of the use of parentheses with AND, OR and NOT operators in searching. 

Example 1: teenagers and high blood pressure

(teenagers OR youth OR adolescent OR juvenile) AND (high blood pressure OR hypertension)

Example 2: dementia and the elderly

(dementia OR alzheimers) AND (elder OR elderly OR older OR geriatric OR senior)