URL of this page: http://www.nlm.nih.gov/medlineplus/searchtips.html

Search Tips

What do the links in the 'Refine by Type' box under 'All Results' mean?

Your initial search results show matches from all of the MedlinePlus content areas. The links in the 'Refine by Type' box under 'All Results' represent sets of MedlinePlus content areas, known as collections. The collections help you narrow your search by displaying results exclusively from one collection. For example, you can limit your search results to the latest news by clicking the News link in the 'Refine by Type' box.

MedlinePlus has nine collections:

  • The Health Topics collection contains MedlinePlus Health Topic pages.
  • The External Health Links collection contains links to Web pages from selected government agencies and health-related organizations. These links may include Interactive Tutorials, videos, easy-to-read materials and NIH publications. They appear on MedlinePlus Health Topic pages but they're listed individually in the search results.
  • The Drugs and Supplements collection contains prescription and over-the-counter medication information and information on herbs and supplements.
  • The Medical Encyclopedia collection contains articles and images on hundreds of diseases and conditions.
  • The Videos and Tutorials collection contains interactive tutorials, surgery and anatomy videos, as well as videos produced by selected government agencies and health-related agencies.
  • The News collection contains news articles and recent press announcements from major medical organizations.
  • The MedlinePlus Magazine collection contains articles that appear in the online version of the NIH MedlinePlus Magazine.
  • The Other Resources collection contains links to organizations, directories and databases from MedlinePlus. This collection also contains featured content, such as the NIH MedlinePlus Magazine and MedlinePlus FAQs.
  • The Multiple Languages collection contains links to high quality health information in languages other than English and Spanish.

What do the links in the 'Refine by Keyword' box mean?

The 'Refine by Keyword' box organizes your search results into groups based on the most frequent words in the top 200 results. For example, a search on cholesterol might return a cluster of documents that contain the phrase reduce the amount. Clustering helps you narrow down a large set of results quickly to find what you're looking for.

If there is a plus sign (Plus symbol) next to a cluster, click on it to view smaller clusters.

If there is a vertical line separating two or more clusters, they have the same number of matches for each term. For example, the earlier search on cholesterol might return a cluster labeled: Diabetes | Blood pressure (5).

Click 'remix' to see additional clusters.

Can I search for a phrase?

Yes, you can search for a phrase by enclosing words in quotation marks. For example, "health services research" retrieves pages containing that phrase.

Will the search automatically expand my search words to include synonyms?

Yes, a built-in thesaurus automatically expands your search. The thesaurus contains a list of synonyms from NLM's MeSH® (Medical Subject Headings) and other sources. When there is a match between a search term and a word in the thesaurus, the thesaurus automatically adds the synonym(s) to your search. For example, if you search for the word swelling, results are automatically retrieved for edema.

Is Boolean searching allowed? What about wildcards?

Yes, you can use the following operators: OR, NOT, -, +, *

You do not need to use AND because the search engine automatically finds resources containing all of your search terms.

OR Use when you want either term, but not necessarily both, to appear in the results
Example: Tylenol OR Acetaminophen
NOT or - Use when you do not want a particular term to appear in the results
Examples: flu NOT bird or flu -bird
+ Use when you want the word to appear in your search results exactly as you typed it
Example: +mammogram finds resources containing that exact word; it does not find resources that contain the words mammography or mammoplasty.
* Use as a wildcard when you want the search engine to fill in the blank for you; you must enter at least three letters
Example: mammo* finds mammogram, mammography, etc.
Boolean operators and their use

Can I restrict my search to a specific Web site?

Yes, you can restrict your search to a specific site by adding 'site:' and the domain or URL to your search words. For example, if you want to find breast cancer information in MedlinePlus only from the National Cancer Institute, search on breast cancer site:cancer.gov.

Is the search case sensitive?

The search engine is not case sensitive. The search engine matches words and concepts regardless of capitalization. For example, a search on alzheimer's disease also retrieves pages containing the words Alzheimer's Disease.

What about searching for special characters like ñ?

You can use special characters in your search, but they're not required. When you use diacritics in your search, the search engine retrieves pages that contain those diacritics. The search engine also retrieves pages that contain the term without special characters. For example, if you search on the word niño, your results include pages that contain the word niño or nino.

Will the search check my spelling?

Yes, the search engine suggests replacements when it doesn't recognize your search term.

Why didn't my search find anything? What should I do?

Your search didn't find anything because you spelled a word incorrectly or because the information you're looking for isn't available in MedlinePlus.

If you spelled a word wrong, the search engine consults the thesaurus for a possible match and makes suggestions. If the search engine doesn't give you suggestions, consult a dictionary for the correct spelling. You can try the medical dictionary on MedlinePlus.

If the information you're looking for isn't available on MedlinePlus, you can try searching other resources from the National Library of Medicine. For example, you can search MEDLINE/PubMed, NLM's database of biomedical journal literature.