The Medical Dictionary for Regulatory Activities (MedDRA) is the international standardised terminology used by regulatory authorities and the pharmaceutical industry for coding adverse event data. MedDRA Version 29.1, released in September 2026, represents a significant update to this critical pharmacovigilance tool. This article provides a comprehensive analysis of the changes introduced in Version 29.1, including terminology updates, Standardised MedDRA Query (SMQ) modifications, the reversal of medication error term classifications, new translations, and LLT currency status changes.
We examine the regulatory and clinical implications of these changes for pharmacovigilance professionals, including the importance of accurate coding for signal detection, the impact on medication error reporting, and the global expansion of MedDRA through new language translations. Drawing on the official MedDRA documentation and published literature, this article offers practical guidance for navigating the updated terminology and ensuring compliance with regulatory requirements.
1. Introduction: The Role of MedDRA in Global Pharmacovigilance
The Medical Dictionary for Regulatory Activities (MedDRA) is a clinically validated, internationally standardised medical terminology developed under the auspices of the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH). It is the cornerstone of adverse event coding, enabling consistent and accurate reporting of adverse drug reactions (ADRs) across the global pharmacovigilance ecosystem.
MedDRA’s hierarchical structure includes five levels:
| Level | Description | Example |
|---|---|---|
| System Organ Class (SOC) | Highest level; grouped by aetiology, manifestation site, or purpose | Infections and infestations |
| High Level Group Term (HLGT) | Superordinate level grouping related HLTs | Viral infectious disorders |
| High Level Term (HLT) | Superordinate level grouping related PTs | Influenza viral infections |
| Preferred Term (PT) | Distinct medical concept | Influenza |
| Lowest Level Term (LLT) | Most specific; synonyms, lexical variants | Flu, Influenza A, Influenza B |
Version 29.1, released in September 2026, is a simple change version, meaning modifications are made only at the PT and LLT levels. This contrasts with complex change versions, where changes may occur at any level of the hierarchy. This article provides a detailed analysis of the changes introduced in this release and their implications for pharmacovigilance practice.
2. Overview of Version 29.1
2.1 Change Request Statistics
MedDRA changes result from user change requests, proactivity requests, and internal MSSO maintenance activities. For Version 29.1:
| Metric | Number |
|---|---|
| Total change requests processed | 1,065 |
| Change requests approved and implemented | 753 |
| Change requests not approved | 300 |
| Change requests suspended for future resolution | 12 |
2.2 Terminology Changes Summary
The net impact on the MedDRA terminology between Versions 29.0 and 29.1 is summarised below:
| File/Level | Version 29.0 | Version 29.1 | Net Change |
|---|---|---|---|
| HLGTs | 337 | 337 | 0 |
| HLTs | 1,739 | 1,739 | 0 |
| PTs | 27,361 | 27,504 | +143 |
| LLTs | 91,082 | 91,499 | +417 |
| SMQ Content Records | 98,140 | 98,554 | +414 |
| Total MedDRA History Records | 142,087 | 142,768 | +681 |
The addition of 143 new Preferred Terms and 417 new Lowest Level Terms reflects ongoing efforts to capture emerging medical concepts, improve coding precision, and address user-identified gaps in the terminology.
3. Key Developments in Version 29.1
3.1 Standardised MedDRA Queries (SMQs)
SMQs are validated, standardised sets of MedDRA terms developed to assist in identifying and retrieving potentially relevant safety information. They are essential tools for signal detection and evaluation.
Key SMQ Statistics for Version 29.1:
| SMQ Level | Version 29.0 | Version 29.1 | Net Change |
|---|---|---|---|
| Level 1 SMQ topics | 101 | 101 | 0 |
| Sub-SMQs (Level 2) | 82 | 82 | 0 |
| Sub-SMQs (Level 3) | 30 | 30 | 0 |
| Sub-SMQs (Level 4) | 16 | 16 | 0 |
| Sub-SMQs (Level 5) | 2 | 2 | 0 |
| Total SMQs | 230 | 230 | 0 |
No new SMQs were added in Version 29.1. However, 177 approved PT changes were made to existing SMQs. These changes reflect ongoing refinements to improve the sensitivity and specificity of SMQ-based searches. Users should review the MedDRA 29.1 Version Report to understand modifications relevant to their therapeutic areas.
With the release of Version 29.1, there are 110 Level 1 SMQ topics (i.e., main topics) with a total of 230 SMQs, including sub-SMQs under the Level 1 SMQs.
Practical Implication: When updating databases and analysis tools, ensure that SMQ content reflects Version 29.1 changes to maintain accurate signal detection. The 177 PT changes may affect the composition of specific SMQs, potentially altering the results of signal detection algorithms.
3.2 Reversal of Moved Medication Error / Issue Terms
One of the most significant changes in Version 29.1 is the reversal of several LLT moves that occurred in Version 29.0.
3.2.1 Background: The 29.0 Changes
In MedDRA Version 29.0, several Lowest Level Terms containing descriptive qualifiers such as “wrong” and “incorrect”—as well as certain descriptive LLTs without qualifiers—were moved from “error” Preferred Terms to “issue” Preferred Terms. This change was based on MedDRA user requests and was intended to improve the representation of these concepts.
3.2.2 The 29.1 Reversal
Following a detailed review by a group of medication error experts from industry and regulatory agencies across ICH regions, these LLT changes were reversed in Version 29.1. The expert group determined that these concepts—including terms with the word “wrong” within the HLGT Medication errors and other product use errors and issues—are considered errors when reported in pharmacovigilance single case reports.
This conclusion was further supported by a data-driven understanding of the use of the terms in cases coded to these LLTs.
3.2.3 Examples of Reversed Terms
| LLT Name | Version 29.0 PT | Version 29.1 PT (Reversed) |
|---|---|---|
| Accidental dose decrease | Dosing error | Wrong dose |
| Drug maladministration | Product administration issue | Product administration error |
| Expired drug dispensed | Product dispensing issue | Product dispensing error |
| Drug not dispensed in original container | Product dispensing issue | Product dispensing error |
| Incorrect storage of drug | Product storage issue | Product storage error |
| Drug stored in wrong location | Product storage issue | Product storage error |
3.2.3 Clinical and Regulatory Significance
This reversal has important implications for pharmacovigilance:
| Implication | Description |
|---|---|
| Medication error reporting | The reversal ensures that medication errors are correctly classified as errors, not merely “issues.” This distinction is critical for accurate signal detection and regulatory reporting. |
| Data consistency | The reversal restores consistency with historical data coded using pre-29.0 versions. |
| Signal detection | Accurate classification of medication errors as errors improves the ability to detect patterns and trends in medication-related harm. |
| Regulatory compliance | The change aligns with the expectations of regulatory authorities for accurate medication error reporting. |
Looking Ahead: The MSSO and the ICH M1 Points to Consider Working Group are currently reviewing the entire HLGT Medication errors and other product use errors and issues. This review may result in further changes to medication error/issue terms and the possible addition of new or adapted concept descriptions to clarify term interpretation.
3.3 Proactivity Requests
The proactive maintenance process allows MedDRA users to propose general changes to MedDRA outside of the established change request process. These proactivity requests may address inconsistencies, make corrections, or suggest improvements.
For Version 29.1:
- No proactivity proposals were implemented.
The MSSO continues to encourage users to submit proactive improvement ideas via the MSSO Help Desk, with specific descriptions and justifications.
3.4 New MedDRA Translations Deployed and Under Development
The MSSO continues to work on new MedDRA translations to enable more users to apply MedDRA in their native language and facilitate global communication of MedDRA-coded data.
3.4.1 Languages Expected by End of 2026
| Language | Status | Expected Release |
|---|---|---|
| Bulgarian | In development | Before end of 2026 |
| Romanian | In development | Before end of 2026 |
With the release of these two languages, there will be 29 MedDRA languages available to users.
Context: Bulgarian and Romanian are part of the 17 European Economic Area (EEA) official languages, approved for translation by the MedDRA Steering Committee in 2020. These translations are needed to support the electronic product information initiative, which includes the translation of MedDRA terms only and does not include MedDRA user documentation.
3.4.2 Other Translations in Development
| Language | Status |
|---|---|
| Danish | In development |
| Maltese | In development |
| Uzbek | In development |
Practical Implication: The expansion of MedDRA translations supports global pharmacovigilance by enabling healthcare professionals and regulators to code and analyse adverse event data in their native languages, improving data quality and facilitating international collaboration.
4. Summary of Changes: Impact on MedDRA Terminology
4.1 Impact on Records in MedDRA Files
The following table summarises the impact of Version 29.1 on the records in MedDRA files:
| File Name | Number of Records in Table |
|---|---|
| hlgt.seq | 0 |
| hlgt_hlt.seq | 0 |
| hlt.seq | 0 |
| hlt_pt.seq | 398 |
| llt.seq | 672 |
| mdhier.seq | 430 |
| pt.seq | 253 |
| soc.seq | 0 |
| soc_hgt.seq | 0 |
| intl_ord.seq | 0 |
A zero indicates that the file has not changed since the prior consolidated MedDRA release.
4.2 LLT Currency Status Changes
Thirteen terms at the LLT level in MedDRA Version 29.1 had a change in currency status. These changes reflect efforts to improve precision, eliminate ambiguity, and align with MedDRA naming conventions.
| Lowest Level Term | New Currency Status | Rationale |
|---|---|---|
| Acetaminophen | Non-current | Drug name, not within MedDRA scope; LLT Acetaminophen drug level added as substitute |
| Cervical stricture | Non-current | Ambiguous term; “cervical” should identify neck location, not uterine location |
| Closed capsulotomy | Non-current | Anatomically imprecise; new term Closed breast capsulotomy added |
| Coloboma of optic disc | Current | Valid concept; represents congenital structural anomaly of the optic nerve |
| Congenital intrahepatic shunt | Non-current | Imprecise term; new PT Congenital intrahepatic portosystemic shunt added |
| Encephalitis post measles | Non-current | Temporal relationship, not specific diagnosis; placement under Subacute sclerosing panencephalitis was inappropriately narrow |
| Fever malignant | Non-current | Ambiguous; can refer to neoplastic fever or dangerous fevers |
| Paracetamol | Non-current | Drug name, not within MedDRA scope; LLT Paracetamol drug level added as substitute |
| Post measles encephalitis | Non-current | Temporal relationship, not specific diagnosis |
| Salicylate | Non-current | Drug name, not within MedDRA scope; LLT Salicylate drug level added as substitute |
| Spiritual experience | Non-current | Broad and ambiguous concept without additional context |
| Walking aid support | Non-current | Ambiguous; new LLT Therapeutic use of walking aid added |
| Wrong technique in product usage process performed in error | Non-current | Pleonasm (includes both “wrong” and “performed in error”) |
Key Observations:
- Drug names removed: Three drug names (Acetaminophen, Paracetamol, Salicylate) were made non-current because drug names are not within MedDRA’s scope. New “drug level” LLTs were added to capture the intended concept.
- Ambiguous terms clarified: Several terms were made non-current due to ambiguity, with new, more precise terms added as substitutes (e.g., Closed breast capsulotomy, Congenital intrahepatic portosystemic shunt, Therapeutic use of walking aid).
- One term restored to current: Coloboma of optic disc was changed from non-current to current, recognising it as a valid concept.
- Naming convention alignment: Cervical stricture was made non-current to align with MedDRA naming conventions (cervical = neck; cervix = uterine).
- Pleonasm removed: Wrong technique in product usage process performed in error was made non-current to avoid redundancy.
5. MedDRA Term Counts by SOC (Selected Examples)
The following table provides selected examples of MedDRA term counts by System Organ Class (SOC) for Version 29.1:
| SOC | LLTs (Primary) | PTs (Primary) | HLTs | HLGTs |
|---|---|---|---|---|
| Blood and lymphatic system disorders | 1,308 | 347 | 87 | 7 |
| Cardiac disorders | 1,668 | 411 | 74 | 10 |
| Congenital, familial and genetic disorders | 4,866 | 1,971 | 100 | 19 |
| Infections and infestations | 8,018 | 2,267 | 150 | 12 |
| Investigations | 15,748 | 6,600 | 106 | 23 |
| Neoplasms (benign, malignant, unspecified) | 9,327 | 2,198 | 201 | 39 |
| Nervous system disorders | 4,319 | 1,189 | 108 | 20 |
| Psychiatric disorders | 2,553 | 590 | 77 | 23 |
| Surgical and medical procedures | 6,726 | 2,725 | 141 | 19 |
| Vascular disorders | 1,514 | 359 | 68 | 11 |
Total LLTs: 91,499 | Total PTs: 27,504
6. Implications for Pharmacovigilance Practice
6.1 For MedDRA Users
| Implication | Action |
|---|---|
| Review changes in your therapeutic area | Use the MedDRA Version Analysis Tool (MVAT) to compare Versions 29.0 and 29.1 |
| Identify new terms relevant to your products | Review the Version Report included in the download |
| Understand SMQ modifications | Review the 177 PT changes to existing SMQs |
| Update coding databases and dictionaries | Download and implement Version 29.1 |
| Train coding and safety staff | Educate staff on the reversal of medication error term classifications |
| Assess impact on legacy data | Consider recoding if necessary for analysis |
6.2 The Medication Error Term Reversal: A Critical Update
The reversal of medication error term classifications is particularly significant for:
| Stakeholder | Impact |
|---|---|
| Pharmacovigilance professionals | Must ensure that medication errors are correctly coded as errors, not issues |
| Regulatory authorities | Will expect accurate classification of medication errors in ICSRs |
| Pharmaceutical companies | Must update coding practices to reflect the reversed terms |
| Signal detection teams | Will benefit from more accurate classification of medication errors |
6.3 Global Impact of New Translations
The addition of Bulgarian and Romanian translations will:
- Facilitate local reporting: Enable healthcare professionals in Bulgaria and Romania to code ADRs in their native languages
- Improve data quality: Reduce errors associated with translation and interpretation
- Support regulatory compliance: Align with EU requirements for electronic product information
- Enhance global collaboration: Facilitate data sharing across linguistic boundaries
7. Conclusion: The Evolving Language of Drug Safety
MedDRA Version 29.1 represents another step forward in the ongoing effort to maintain a medical terminology that is precise, comprehensive, and reflective of current clinical practice and regulatory needs.
Key Takeaways from Version 29.1:
| Takeaway | Significance |
|---|---|
| 143 new PTs and 417 new LLTs | Enhanced coding precision for emerging medical concepts |
| Reversal of medication error term classifications | Restores accurate classification of errors vs. issues in pharmacovigilance |
| 177 PT changes to existing SMQs | Refined signal detection capabilities |
| 13 LLT currency status changes | Improved precision and removal of ambiguous terms |
| Bulgarian and Romanian translations | Expanding global accessibility of MedDRA |
For pharmacovigilance professionals, staying current with MedDRA updates is essential for:
- Accurate adverse event coding
- Effective signal detection
- Regulatory compliance
- Global data sharing and analysis
As the language of medicine evolves, so too must the tools we use to describe it. MedDRA Version 29.1 ensures that the global pharmacovigilance community has the vocabulary needed to protect patient safety in an era of rapid therapeutic innovation.
