No, NLM doesn’t peer-review articles; many records link to peer-reviewed journals, while some content and preprints are not.
The U.S. National Library of Medicine (NLM) runs several well-known platforms: PubMed, MEDLINE, PubMed Central (PMC), Bookshelf, and MedlinePlus. People often assume everything they find through these channels has passed peer review. That’s not quite right. NLM curates, indexes, and preserves literature. It doesn’t run peer review for the journals it indexes or the summaries it hosts. Many items you see will come from journals that do use peer review. Others won’t, such as preprints or consumer health pages. This guide clears up the differences, shows you how to spot peer-reviewed content, and teaches quick checks you can use before you cite or share.
What Each NLM Platform Actually Provides
Think of NLM as an umbrella with multiple tools underneath. Each tool serves a different job. That job shapes whether you’re looking at peer-reviewed science, author manuscripts, or lay summaries.
| Platform | What It Holds | Peer Review Status |
|---|---|---|
| PubMed | Searchable citations and abstracts from MEDLINE, PMC, and more | Many items point to peer-reviewed journals; you can’t filter only peer-reviewed by default |
| MEDLINE | Curated journal citations selected by NLM’s committee | Indexing favors journals with peer-reviewed content and publishing standards |
| PubMed Central (PMC) | Free full-text articles and author manuscripts | Large share from peer-reviewed journals; also includes preprints and funded author manuscripts |
| Bookshelf | Books, reports, and guidelines | Editorial review varies by publisher; not the same as journal peer review |
| MedlinePlus | Consumer-friendly health pages and links to trusted sources | Expert-reviewed educational content; not journal peer review |
Are NLM Records From Peer-Reviewed Journals? Clarity For Readers
Many PubMed records track back to journals that use editorial peer review. That said, PubMed itself is a search database. It doesn’t label or filter by peer-reviewed status across the board. NLM confirms there isn’t a master list of “peer-reviewed only” titles and no switch to limit a search that way. If you need to cite peer-reviewed work only, you’ll confirm at the journal level or use filters and cues covered later. See NLM’s own note on this point in the article “Are the journals in PubMed peer-reviewed?” which spells out the lack of a peer-review-only filter in plain terms (NLM support KB).
What Counts As Peer Review In MEDLINE Selection
MEDLINE is a core piece of PubMed. Journals don’t just appear there by accident. They go through an application and evaluation process. Part of that process expects a track record of peer-reviewed content and consistent editorial practice, such as abstracts for peer-reviewed items and steady publication. These are journal-level expectations, not article-by-article verdicts from NLM. You can read the current criteria on NLM’s site under the MEDLINE application process, which includes thresholds like a set number of peer-reviewed articles and other publishing basics (MEDLINE application criteria).
Why PMC Includes Both Journal Articles And More
PMC hosts full-text articles from participating journals and author manuscripts deposited to meet funder public-access rules. During the pandemic era, NLM also tested adding preprints related to NIH-supported work and later expanded the pilot. Preprints deliver speed but haven’t gone through journal peer review. PMC and PubMed mark these records with clear banners so readers can spot them at a glance. NLM covered that pilot and the display cues in public updates and interviews, and those banners remain a handy signal when you land on a preprint record (NIH Preprint Pilot update).
MedlinePlus Isn’t A Journal And Uses A Different Review Model
MedlinePlus is NLM’s consumer health site. It’s written and curated for patients, families, and the public. It uses expert review and frequent updates, but that process isn’t journal peer review. You’ll find a clear description of how pages are created, licensed, and refreshed on the MedlinePlus review page, which breaks down update cycles and quality checks by content type (MedlinePlus review & update).
Fast Way To Tell If A PubMed Record Leads To Peer Review
If you landed on a PubMed record and need a quick read on peer-review status, use these steps. They’re fast and reliable for most cases.
Step 1: Check The Journal Page
Click the journal title on the PubMed record. Follow through to the journal’s site. Look for “About,” “Editorial policies,” or “Instructions for authors.” Most reputable journals spell out blind review, editorial board roles, and article types that get external review. If you can’t find the policy, the journal may not use peer review for all content types, or it may be a poor-fit venue for scholarly citation.
Step 2: Look For Article Type
PubMed labels article types such as “Randomized Controlled Trial,” “Systematic Review,” “Case Report,” and “Editorial.” Many research articles go through peer review. Editorials, news, and letters may not. The label gives you an early clue before you click through.
Step 3: Confirm With MEDLINE Indexing
If the record is marked as indexed in MEDLINE, you’re dealing with a title that passed NLM’s journal-level screening. That’s a good signal for editorial quality. It still doesn’t replace checking the journal’s policy, since some content types aren’t externally reviewed.
Step 4: Watch For Preprint Banners
Preprints in PubMed or PMC carry a banner that flags the lack of peer review. Treat these as preliminary. They’re useful to track new methods or early results. For formal citation in a policy or clinical pathway, wait for the journal version when you can.
Peer Review Myths That Trip People Up
Myth 1: “Everything In PubMed Is Peer-Reviewed”
PubMed is a discovery tool, not a peer-review filter. Many entries link to peer-reviewed journals. Others point to preprints, conference items, or non-research content. NLM’s own support pages state there’s no built-in way to limit only to peer-reviewed journals.
Myth 2: “PMC Only Hosts Peer-Reviewed Articles”
PMC holds peer-reviewed content from journals as well as author manuscripts and preprints from funded research. That mix is handy for access, but you’ll still read the record header for cues and banners.
Myth 3: “MedlinePlus Articles Are The Same As Journal Papers”
MedlinePlus offers health education, not research articles. It undergoes expert review and routine updates, but the process is designed for plain-language accuracy. It isn’t a journal workflow with external referees and multi-round reports.
How To Confirm Peer Review Before You Cite
Use this quick checklist when you need a clean audit trail. It works across topic areas and keeps you from guessing based on a logo or database badge.
| Step | Where To Check | What To Look For |
|---|---|---|
| Journal Policy | Journal’s “About” or “Editorial policies” page | Statement that research articles are peer-reviewed; review model (single-blind, double-blind, open) |
| Indexing Signal | PubMed record badge for MEDLINE; journal listing | Inclusion in MEDLINE; consistent publishing schedule; abstracts for reviewed content |
| Article Type | PubMed “Publication types” and journal landing page | Research, trial, or systematic review vs. editorial, news, or letter |
| Preprint Warning | PMC/PubMed record header | Banner noting “not peer reviewed” for preprints |
| Final Version | Publisher page | Volume/issue/page or article number; DOI that points to a journal version |
How MEDLINE Vetting Helps, And Where It Stops
MEDLINE’s selection adds confidence that a journal follows sound editorial practice. The process looks at peer-review activity, publication ethics, timeliness, and article structure. It’s a journal-level green light, not a guarantee that every single item inside that journal went through external review. Many journals publish news columns or opinion pieces alongside research. Those pieces can be useful background but aren’t peer-reviewed research.
PMC Preprints: What To Do With Them
Preprints give early access to new ideas and data. They can be citable in some settings, with clear labeling. For clinical or policy work that needs vetted evidence, give preference to the journal-reviewed version when it becomes available. If you decide to cite a preprint, add a note in your document that it hasn’t been peer-reviewed. That small line prevents confusion for your readers.
MedlinePlus Pages: When They’re Ideal
When you need plain-language guidance for patients or a quick refresher on a condition, MedlinePlus is a solid first stop. Pages are reviewed by subject experts and updated on a schedule. That process is different from journal peer review, yet it aims for accuracy and clarity. If you need primary research to back a policy, move from MedlinePlus to PubMed and pull the underlying studies it links to. MedlinePlus also teaches readers how to test the quality of health sites, which you can share with clients or students who ask how to judge sources (Evaluating health information).
Smart Filters And Search Moves In PubMed
Use Publication Types
In PubMed’s sidebar, select publication types such as “Clinical Trial,” “Randomized Controlled Trial,” or “Systematic Review.” These tend to be peer-reviewed. You’ll still verify on the journal page, but this narrows the field fast.
Favor MEDLINE-Indexed Records
Toggle the “MEDLINE” subset when available, or spot the “Indexed for MEDLINE” flag on records. That flag signals the journal passed NLM’s selection process, which includes peer-review expectations.
Scan The Journal’s Instructions For Authors
Most journals lay out review models under author guidance. A quick skim confirms if research articles get external referee reports and what content types bypass external review.
Watch For The Green Banner On Preprints
Preprint records in PMC and PubMed show a clear notice that the item hasn’t been peer-reviewed. Treat these differently from the later journal article. When the journal version appears, update your citation.
Edge Cases You’ll See
Conference Abstracts
Abstracts may be screened by a program committee. That’s not the same as full peer review. If a full paper appears later in a journal, cite that version for stronger support.
Author Manuscripts
Funder policies often require authors to deposit a manuscript after acceptance. These are peer-reviewed in the journal workflow, yet the PMC version may show the accepted manuscript rather than the final typeset article. Link to the version of record when precision matters.
Editorials And Letters
These can be insightful and timely. Many aren’t peer-reviewed. Use them to understand a debate, then gather primary studies before making evidence claims.
Takeaways You Can Trust
- NLM is a steward and indexer. It doesn’t run peer review for the literature it hosts or points to.
- Many PubMed entries map to journals with formal peer review. You still confirm on the journal site.
- MEDLINE’s selection process expects journals to publish peer-reviewed content and maintain sound practice.
- PMC includes journal articles, author manuscripts, and preprints. Preprints carry clear banners.
- MedlinePlus delivers expert-reviewed education for the public. It isn’t a journal workflow.
- When in doubt, follow the checklist above to verify before you cite.
Method Notes
This guide draws on NLM’s public pages and program updates. You can review NLM statements on the lack of a peer-review-only filter in PubMed, the MEDLINE selection rules that expect peer-reviewed content, and NLM updates about the preprint pilot that introduced clearly labeled preprints into PMC and PubMed. Those pages are linked above so you can read the original wording in context.