How to Search Scientific Literature With PubMed
PubMed is a free search tool for biomedical and health research. It is widely used by students in medicine, pharmacy, nursing and public health, because it lets you find published studies on almost any health topic. A good search saves time and gives you better sources for essays, theses and clinical questions. This guide explains how to plan a search, build it step by step, and keep what you find. Websites change, so check the buttons and menus on the live page.
What PubMed is, and what it is not
PubMed is a search interface to a large database of references and abstracts, run by the United States National Library of Medicine. For each article it usually gives the title, authors, journal, abstract and links to the publisher. It does not host every full article. Some are free to read, and others need a subscription, which your university library may provide. Always read the abstract, and then the full text if you plan to use the study.
Step 1: Turn your topic into a clear question
Vague topics give vague results. Write your question in one sentence, and break it into parts. A common method for clinical questions is PICO.
| Part | Meaning | Example |
|---|---|---|
| P | Population or problem | Adults with high blood pressure |
| I | Intervention or exposure | Pharmacist-led counselling |
| C | Comparison | Usual care |
| O | Outcome | Blood pressure control |
Not every question needs all four parts, but writing them down shows you which keywords you need.
Step 2: List keywords and synonyms
For each part, write the main word and its alternatives. Authors use different words for the same idea, so a single keyword will miss relevant papers. For example, hypertension might also be written as high blood pressure, and pharmacist might appear as pharmacists or pharmaceutical care.
Step 3: Combine terms with AND, OR and NOT
PubMed understands three simple operators, written in capital letters.
| Operator | What it does | Example |
|---|---|---|
| OR | Finds records with either term. Use it between synonyms. | hypertension OR "high blood pressure" |
| AND | Finds records with both terms. Use it between different concepts. | hypertension AND pharmacist |
| NOT | Removes records with a term. Use it carefully, because it can remove useful papers. | hypertension NOT pregnancy |
Put synonyms inside brackets and join the groups with AND. Here is an example search for the question above. It is an illustration, not a complete strategy.
(hypertension OR "high blood pressure") AND (pharmacist* OR "pharmaceutical care") AND (counselling OR counseling OR intervention*)
Two small tricks help. Quotation marks keep a phrase together, and an asterisk after a word stem, such as pharmacist*, finds several endings.
Step 4: Use field tags and MeSH terms when you need precision
PubMed lets you say where a word must appear. Adding [tiab] after a term searches only titles and abstracts, which removes records where the word is mentioned in passing. For example, hypertension[tiab].
PubMed also uses Medical Subject Headings, called MeSH. These are standard subject labels that indexers add to articles, so that different wordings are grouped under one heading. You can search for one with [mh], for example hypertension[mh]. Very recent articles may not be indexed yet, so many careful searchers combine MeSH terms and free-text words with OR.
Step 5: Narrow the results with filters
After you search, use the filters on the left or top of the results page. Useful ones include the publication date, article type (such as clinical trial, review or systematic review), species, language, and free full text. Apply filters one at a time, and note which ones you used, so that you can describe your method in a report.
Step 6: Read and judge what you find
- Sort the list by best match or by most recent, depending on your need.
- Read titles and abstracts first, and open only the promising papers.
- Look at the study type, the number of participants, and whether the conclusions follow from the results.
- Check the journal and the authors’ affiliations. If a journal seems unfamiliar, check whether it has a transparent peer-review process.
- Use the similar articles and cited-by features to find related papers.
Step 7: Save your search and your results
Use the Save, Email or Send to options on the results page to keep citations or export them to reference-manager software. Copy your final search string into a document with the date, because you may need to repeat it. A free account lets you save searches and set up alerts for new papers, if you want them.
Step 8: Get the full text
From the article page, use the publisher link or the free full text link if present. If the paper is behind a paywall, check what your university library offers. Never use a website that claims to give illegal copies, since it may break copyright and may carry malware.
Common mistakes
- Using one keyword. Add synonyms joined with OR.
- Putting OR where AND belongs. Use OR within a concept and AND between concepts.
- Trusting titles only. Read the abstract before you decide.
- Not recording the search. Write down the string, the date and the filters.
- Citing a paper you have not read. Read at least the abstract, and the full text for important claims.
Key takeaways
Define a clear question, list synonyms, join them with OR and AND, add field tags or MeSH for precision, filter carefully, and record your search. Good searching is a skill that improves with practice.
This article describes general search practice and is not medical advice. See our Disclaimer.