Skip to main content
The MedDRA Explorer API evolves behind an explicit header so you can trial upcoming payload changes before they become the default. Unless you are validating a preview release, you can stick with the defaults documented in the endpoint reference.

​
Default behaviour

  • Header: X-API-Version
  • Default value: 1
If you omit the header, requests target the current stable API version. The platform maintains backwards compatibility within a major version; new fields are additive and marked as optional.

​
Opting into a preview

When we announce a new API version, set the header to the preview identifier to test the changes: 
curl https://api.meddra.co/codes/10011906 \
  -H "X-API-Version: 2"
Preview versions typically adjust response schemas—adding fields, renaming existing ones, or removing deprecated attributes. The endpoint paths remain the same.

​
Rolling out updates

Before we promote a preview to the default version, we provide:
  • A changelog entry summarising what changed.
  • A deprecation timeline for the previous default.
  • A reminder in the Mintlify documentation.
After we flip the default, the preview identifier stays active for at least one full release cycle so you can finish migrations.

​
Tips for clients

  • Set the header once in your HTTP client or API gateway to keep versioning consistent across requests.
  • Monitor your logs for warnings about upcoming API changes—we emit diagnostics when we detect mismatched expectations.
  • Coordinate with MedDRA versions: API versions and MedDRA releases are independent. You can classify narratives against MedDRA 28.0 while testing API X-API-Version: 2 in the same workflow.
⌘I