What terms does Emtree contain?

Emtree includes terms for: Drugs and medical devices Diseases and biological functions Medical procedures including traditional Chinese practices Study types and much more

How is Emtree structured?

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.

How often is Emtree updated?

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.

How do Emtree and MeSH differ?

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. Learn more about the differences between Emtree and MeSH.

Embase

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 makes things findable

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

Chart showing Embase classes of indexing terms

Embase indexing at a glance

Emtree is expansive, including on average over 4 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.

Download the Embase indexing guide for more insights.(opens in new tab/window)

Comparison of the volumes of results found with drug searches in MEDLINE/PubMed and Embase.

By the numbers: Emtree as of March 2023

96,303 preferred terms including MeSH terms

496,982 synonyms so you don’t have to know the preferred term to obtain relevant results

35,400 drugs and chemicals, linked to almost 26,800 CAS registry numbers

6,000 dedicated terms for general and medical devices (e.g., endoscopes, catheters)

16,000 medical device trade names from over 2,500 manufacturers 66 drug subheadings, 4 medical device subheadings, 14 disease subheadings and 50 check tags for evidence-based medicine