New Feature in PubMed: Proximity Searching

At the end of 2022, the National Library of Medicine (NLM) added proximity search capabilities to PubMed. With proximity search, users can search for two terms appearing within a specified distance from each other in any order in the [Title] or [Title/Abstract] fields. The format for using proximity searching is “search terms”[Field:~n], where n is the maximum number of words that may appear between the search terms.

History and Search Details for two searches. The first is “addiction treatment”[title/abstract], which yielded 3,233 results; the second is “addiction treatment”[title/abstract:~3], which yielded 6,677 results.
In a search that does not take advantage of proximity searching, putting terms in quotations will ensure that the terms appear exactly as written. For example, “addiction treatment”[Title/Abstract] will only retrieve articles that contain the exact phrase “addiction treatment” in the title and/or abstract. However, if you instead search for “addiction treatment”[Title/Abstract:~3], the search will still return results with the exact phrase “addiction treatment,” but also “addiction and treatment,” “treatment for addiction,” “treatment of opioid addiction,” “treatment of substance addiction,” and more!

The first three results for the search “addiction treatment”[title/abstract:~3] include the following phrases in their abstracts: “addiction require specialized treatment,” “addiction treatment,” and “treatment of opioid addiction.”
More than two terms can be included in a proximity search. For example, a search for “drug addiction methadone”[title/abstract:~3] will include results that contain all of those words with no more than three words between each. A result may include the phrases “methadone treatment for drug addiction” or “methadone, an established anti-addiction drug.” However, it is not possible to specify that an exact phrase should appear within a certain distance of another term within a proximity search, as PubMed will treat each word within the quotations as separate terms.

There are some other limits to PubMed’s new proximity search feature. As mentioned previously, it can only be used with the [Title] or [Title/Abstract] field tags. Truncation cannot be used in combination with proximity searching, and if terms in a proximity search include a wildcard (*), the proximity portion of the search will be ignored.

If you are interested in learning more about structuring a proximity search in PubMed, NLM has created an interactive tutorial video that can be completed in less than 10 minutes, or you can Ask a Librarian at HSLS.

~Rachel Suppok