What Is SNOMED CT? Clinical Terminology Explained

What is SNOMED CT? Clinical terms as codes, explained simply

SNOMED CT is the largest clinical terminology in the world, used to record diagnoses, findings, allergies and procedures as codes. How concepts, descriptions and relationships work, examples such as 91936005 for penicillin allergy, licensing, and how SNOMED CT differs from ICD and LOINC.

Written by Anpheros, with sources

Information, not medical advice

Data stored in the EU

by Anpheros Published 26 October 2026 2 min read

Short answer: SNOMED CT is a clinical terminology: a very large, structured list of the concepts doctors record (diseases, findings, symptoms, procedures, allergies, body structures), each with a numeric code. Type 2 diabetes mellitus is 44054006, asthma is 195967001, allergy to penicillin is 91936005. Electronic records use it to store what a clinician wrote in a way a computer can search and share.

How it is organised

SNOMED CT has hundreds of thousands of concepts. Each concept has an ID, one or more descriptions (the terms people use, in several languages) and relationships to other concepts. "Type 2 diabetes mellitus" is a "diabetes mellitus" (73211009), which lets software find all patients with any kind of diabetes. Concepts sit in hierarchies such as clinical finding, procedure, substance and body structure.

SNOMED CT, ICD and LOINC

The three are complementary:

SNOMED CT captures clinical detail at the point of care.
ICD (WHO) is a classification used for statistics, mortality and, in many countries, billing; it groups many SNOMED concepts into one code.
LOINC names tests and measurements.

A record can store a problem in SNOMED CT and map it to ICD-10 for reporting.

Licence

SNOMED CT is owned by SNOMED International, a not-for-profit organisation. Use is free in member countries (most of Europe, the UK, the US, Australia and others) under the national licence; elsewhere an affiliate licence may be needed.

In Anpheros

In Anpheros, allergies and some findings in the record can carry SNOMED CT codes next to the plain-language name, and conditions also carry ICD-10, so a doctor's system can read them. The International Patient Summary uses SNOMED CT for allergies and problems. Developers: FHIR code systems.

Sources

Frequently asked questions

Is SNOMED CT free?

In member countries, yes, through the national licence. In non-member countries an affiliate licence may be needed.

What is the difference between SNOMED CT and ICD-10?

SNOMED CT records clinical detail; ICD-10 classifies diseases for statistics and billing. Many SNOMED concepts map to one ICD code.

Is SNOMED CT available in my language?

Many countries publish translations; the concept codes stay the same in every language.

Why do allergies use SNOMED CT?

Because it can describe the substance and the type of reaction precisely, which international summaries such as the IPS need.

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This guide is for information and does not replace medical advice. For decisions about your health, talk to your doctor. In an emergency, call your local emergency number (112 in Europe).

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