MeSH (Medical Subject Headings) are standardized keywords that you can look up in the MeSH Database. The majority of articles in PubMed (over 90%) have been assigned MeSH terms to provide information on the content of the articles. MeSH terms are manually assigned by indexers of the NLM (National Library of Medicine).
By using MeSH terms in your search, the various synonyms of a term are automatically included in the search query.
Example: In literature the concept of 'cancer' can be described in various ways: cancer, cancers, tumor, tumour, neoplasms etc. If you were to search using the word 'neoplasms' only, you would miss articles. If you search with the MeSH term 'neoplasms', you will find articles on this subject no matter which words were used to describe this concept.
Watch this video from Laupus Health Sciences Library (East Carolina University) for a demo on the MeSH database.
To search PubMed using the selected MeSH terms, click on 'Search PubMed' after selecting the MeSH terms in the MeSH database (with 'Add to Search Builder').
The MeSH Database provides additional information on all MeSH terms (see the Raw Foods example below):
There are several ways to search more specifically with a MeSH term
(see the Intensive Care Unit example below):
Tip: compare the number of results of the four searches mentioned above.
In the MeSH database you can also find Pharmacological Action terms. This is a special type of MeSH that allows you to search for pharmacological action, e.g. "Serotonin Uptake Inhibitors"[Pharmacological Action]. On the information page you can see which drugs are included.
If you would only search with "Serotonin Uptake Inhibitors"[MeSH], then you would miss articles about Prozac for instance ("Fluoxetine"[MeSH]).
A supplementary concept is a preliminary stage of a full MeSH term. Supplementary concept is often used for rare diseases and drugs, e.g. Moderna's COVID-19 vaccine: "mRNA-1273 vaccine" [Supplementary Concept]. It is possible to search with this term and on the information page you can see under which MeSH this Supplementary Concept term is grouped.
The last category of terms are publication type terms. These are used to indicate the publication type, e.g. "Randomized Controlled Trial" [Publication Type].