It has been reported in the journal literature and on scholarly publishing blogs that PubMed contains articles from predatory journals. In short, articles from potentially predatory publishers may appear in PubMed, although they are not part of MEDLINE.
We turn to PubMed as an authoritative source for biomedical literature, so what happened? Simply put, there is a “backdoor” for getting journals listed in PubMed. PubMed is the publicly accessible platform of the MEDLINE database from the National Library of Medicine. However, PubMed is also a portal for finding PubMed Central articles in journals that are not indexed in MEDLINE. When searching MEDLINE on platforms such as Ovid, Scopus, or EBSCO, you are likely searching only MEDLINE, depending on your search filters. In PubMed, by default, you are searching MEDLINE and PubMed Central together, in addition to other collections. When you see the [Indexed for MEDLINE] tag below the abstract, you can tell that an article is from a publication indexed in MEDLINE, such as this one. Very new records will not have this tag, but may be from a journal indexed in MEDLINE. You can also see if a journal is indexed in MEDLINE by looking it up in the NLM catalog.
If you have questions about MEDLINE or searching the biomedical literature, contact a librarian.