The Emtree life science thesaurus indexes full text for a more thorough search
Emtree is Elsevier’s authoritative life science thesaurus. With Emtree indexing, you can use natural language to search thousands of journals and millions of conference abstracts with precision and high recall.
Emtree terms are used to index:
All drug generic names described by the FDA and EMA
All drug international non-proprietary names (INNs) described by the WHO
Drug trade names for most major pharmaceutical companies
Medical device trade and general names, plus medical procedures
Global medical device nomenclature (GMDN) names used by the FDA
Diseases, organisms, biological functions, and medical and biological parameters
Terms for traditional Chinese medicine
All terms from the MEDLINE thesaurus MeSH
Embase indexing at a glance
Emtree is expansive, including on average more than four synonyms for each term to ensure that your results are comprehensive. Both Embase records and licensed MEDLINE records are indexed extensively, either via expert manual indexing or advanced algorithms.
Core principles of Embase indexing:
Indexers check the full article, not just title and abstract. Indexers are warned if they attempt to index terms in the wrong field or if terms cannot be found in Emtree. Data samples are checked monthly to provide continuous feedback to indexers.
The Emtree thesaurus controls the index terms for consistent concept coverage.
By the numbers: Emtree as of February 2025
103,133 preferred terms including MeSH terms
552,048 synonyms so you don’t have to know the preferred term to obtain relevant results
36,728 drugs and chemicals preferred terms, linked to almost 26,800 CAS registry numbers
66,405 device (e.g., endoscopes, catheters) and general preferred terms
21,578 medical device trade names 64 drug subheadings, 4 medical device subheadings, 14 disease subheadings
"Subheadings in databases like Embase provide the most useful support for finding adverse events, but not every database has indexing or subheadings."
SG
Su Golder
Research Fellow at University of York
Frequently asked questions
Emtree includes terms for:
Drugs and medical devices
Diseases and biological functions
Medical procedures including traditional Chinese practices
Study types and much more
Our experts use a polyhierarchical representation of biomedical knowledge to index the full text of journal articles in Embase. A term can appear in multiple branches. Structure changes are infrequent but can happen to remain accurate.
Emtree is updated three times a year. New terms are added based on their frequency of use. The focus is on drugs, medical devices, procedures and diseases.
Both are hierarchical controlled vocabularies for health sciences and have a similar facet structure. In fact, Embase was modeled on MeSH in 1988. Both also link to CAS registry and Enzyme Commission numbers.
Over time, however, Embase has differentiated itself from MeSH. While it still includes all MeSH terms, it has become a more extensive thesaurus that facilitates a more intuitive way of exploring the literature.