# MedDRA (Medical Dictionary for Regulatory Activities)

> MedDRA is the ICH-governed international medical terminology used by regulatory authorities and the
> biopharmaceutical industry to code adverse events and report drug safety. It is maintained by the MedDRA
> Maintenance and Support Services Organization (MSSO), which releases a new dictionary version every March
> and September in English and more than a dozen translations. The MSSO publishes a REST API so subscribers
> can embed term search, hierarchy navigation, SMQ analysis and version-impact reporting in their own
> pharmacovigilance and clinical systems.

This file was generated by API Evangelist from MedDRA's own published surface on 2026-09-17. MedDRA does not
publish an llms.txt of its own (probed https://www.meddra.org/llms.txt — the site is an Angular single-page
app that returns its HTML shell with HTTP 200 for any path, which is a soft-404, not a document).

## What you have to know before calling anything

- MedDRA is licensed, not open. Every operation except the status check requires an OAuth 2.0 bearer token
  issued by https://mid.meddra.org/ against an active MSSO subscription (scope `meddraapi`).
- A subscription is free for regulatory authorities, non-profits, educational institutions and direct
  patient-care providers, and priced on a published sliding scale by parent-company revenue for commercial
  organisations ($139 to $63,800 per year). Organisations headquartered in Japan subscribe through the JMO.
- The terminology itself is copyrighted. Redistributing MedDRA content retrieved through the API is governed
  by the MedDRA licence, not by the API's technical terms.
- The API is READ-ONLY. Ten of its sixteen operations are POSTs, but they post a query body and return data;
  nothing in this API creates, changes or deletes anything. Do not treat POST here as a mutation.

## APIs

- [MedDRA API](https://www.meddra.org/meddra-apis): sixteen operations — term and SMQ search, term detail,
  parent/child/hierarchy lookup, hierarchy analysis, SMQ analysis, term history, language and release
  listings, data-file download, search export, data-impact and version reports, subscription validation, and
  an unauthenticated status check.
- Base URL: https://mapisbx.meddra.org — the non-GxP "Production" environment (formerly called Sandbox).
- OpenAPI 3.0.1: https://mapisbx.meddra.org/swagger/v1/swagger.json
- Swagger UI: https://mapisbx.meddra.org/index.html
- A separate GxP-assessed environment carries four of these APIs (Details, Search, Status, Type) for use
  inside validated systems. Its host is documented only in the subscriber-only programmer guide.

## The data model

MedDRA is a five-level hierarchy — System Organ Class (SOC) → High Level Group Term (HLGT) → High Level Term
(HLT) → Preferred Term (PT) → Lowest Level Term (LLT) — crossed by Standardised MedDRA Queries (SMQs), which
group terms for safety analysis. Every term is an 8-digit numeric code, and every code is meaningful only
within a stated dictionary version and language, both of which are request parameters on nearly every
operation. GET /api/rel lists the supported versions; GET /api/lang lists the translations.

## Documentation

- MedDRA APIs overview: https://www.meddra.org/meddra-apis
- Summary of API Functions (which APIs are in which environment):
  https://files.meddra.org/www/Website%20Files/APIs/Summary%20of%20API%20Functions%20v2.pdf
- Detailed programmer guides (subscriber login required): https://www.meddra.org/private/api-info
- Subscription types: https://www.meddra.org/subscription/subscription-type
- Subscription rates: https://www.meddra.org/subscription-rates
- Downloads and MSSO tools: https://www.meddra.org/software-packages
- Help desk: https://www.meddra.org/contact — put "APIs" in the subject line.

## Operational facts worth knowing

- Throttling: every operation declares a 429 response. The limits themselves are published only in the
  subscriber-only programmer guides; no RateLimit-* or Retry-After header is declared or observed.
- Errors: no RFC 9457 problem+json and no error body schema at all. The contract distinguishes several 400
  meanings ("Failed Model Validation", "Language/Version Does Not exist", "Insufficient Authorization",
  "Invalid Input") as separate documentation entries, but a client sees only the status code on the wire.
- Versioning: the API contract is unversioned (info.version "1", no /v1 prefix). What changes on a cadence is
  the dictionary, twice a year, and old versions stay addressable through the `ver` parameter.
- No status page, no SDKs in any package registry, no MCP server, no agent card, no changelog for the API
  itself. What the MSSO does publish on a schedule is the dictionary release and its "What's New" document.

## Repository artifacts (API Evangelist)

- OpenAPI (harvested verbatim): openapi/_original/meddra-api-openapi.json
- Authentication and OAuth scopes: authentication/, scopes/
- Error catalog: errors/meddra-problem-types.yml
- Conventions, lifecycle, changelog, conformance, sandbox: conventions/, lifecycle/, changelog/, conformance/, sandbox/
- Plans and rate limits: plans/, rate-limits/
- Data model: data-model/meddra-data-model.yml
- Candidate MCP tool list (derived, nobody ships a server): mcp/meddra-mcp.yml