The Medical Dictionary for Regulatory Activities (MedDRA) is the internationally recognized medical terminology developed under the auspices of the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH). Used extensively in pharmacovigilance, clinical trials, and regulatory submissions, MedDRA enables consistent coding, analysis, and communication of adverse event data across the global healthcare community.
Version 29.0, released in March 2026, introduces significant terminology updates, including new terms, revised hierarchies, changes to Standardised MedDRA Queries (SMQs), and important modifications to medication error concepts.
1. Introduction: The Role of MedDRA in Global Pharmacovigilance
The Medical Dictionary for Regulatory Activities (MedDRA) is a clinically validated, standardized medical terminology developed to facilitate the sharing of regulatory information internationally. It is used for medical coding of adverse event information during all phases of drug development, from pre-marketing clinical trials to post-marketing surveillance .
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 (single symptom, sign, diagnosis) | Influenza |
| Lowest Level Term (LLT) | Most specific; synonyms, lexical variants | Flu, Influenza A, Influenza B |
Version 29.0 represents a significant update to this terminology, incorporating user feedback, addressing inconsistencies, and reflecting evolving medical knowledge. This article analyzes the key changes and their implications for pharmacovigilance professionals.
2. Overview of Version 29.0 Changes
MedDRA Version 29.0 is a complex change version, meaning modifications may occur at any level of the MedDRA hierarchy .
2.1 Change Request Statistics
| Metric | Number |
|---|---|
| Total change requests processed | 1,380 |
| Change requests approved and implemented | 1,042 |
| Change requests not approved | 333 |
| Change requests suspended for future resolution | 5 |
2.2 Net Impact on Terminology
The following table summarizes the net changes to MedDRA terminology in Version 29.0:
| File/Level | Version 28.1 | Version 29.0 | Net Change |
|---|---|---|---|
| HLGTs | 337 | 337 | 0 |
| HLTs | 1,739 | 1,739 | 0 |
| PTs | 27,163 | 27,361 | +198 |
| LLTs | 90,471 | 91,082 | +611 |
| SMQ Content Records | 97,480 | 98,140 | +660 |
| Total MedDRA History Records | 141,148 | 142,087 | +939 |
Key Observation: The addition of 198 new Preferred Terms and 611 new Lowest Level Terms reflects ongoing efforts to capture emerging medical concepts and improve coding precision.
3. Complex Changes in Version 29.0
Complex changes involve modifications to the hierarchical structure of MedDRA. Two complex changes were implemented in Version 29.0 following public consultation (8 September – 31 October 2025) .
3.1 New High Level Term: Poliovirus Infections
| New HLT | SOC |
|---|---|
| Poliovirus infections | Infections and infestations |
3.2 Merged High Level Term
| Original HLT | Merged Into | SOC |
|---|---|---|
| Poliomyelitis viral infections | Poliovirus infections | Infections and infestations |
Rationale: Replacing HLT Poliomyelitis viral infections with new HLT Poliovirus infections conforms to MedDRA term naming conventions and reflects taxonomic classification as well as standard medical usage. Polio viruses are a group of viruses that cause poliomyelitis, a highly infectious disease that can affect the nervous system and lead to paralysis .
Clinical Implication: This change improves the accuracy of coding for poliovirus-related conditions and aligns MedDRA with current virological nomenclature.
4. Standardised MedDRA Queries (SMQs) Updates
SMQs are validated, standardized sets of MedDRA terms developed to assist in identifying and retrieving potentially relevant safety information .
4.1 SMQ Statistics in Version 29.0
| SMQ Level | Version 28.1 | Version 29.0 | 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 |
4.2 Changes to Existing SMQs
While no new SMQs were added, 255 PT changes were approved to existing SMQs. Users should review the MedDRA 29.0 Version Report to understand modifications relevant to their therapeutic areas.
Practical Guidance: When updating databases and analysis tools, ensure that SMQ content reflects Version 29.0 changes to maintain accurate signal detection.
5. Medication Error and Issue Terms: Significant Reorganization
Based on user requests, the MSSO undertook a comprehensive reorganization of Lowest Level Terms within the HLGT Medication errors and other product use errors and issues .
5.1 Key Principles of Reorganization
Terms were realigned to clearly distinguish between:
- “Error” concepts (accidental, unintentional)
- “Issue” concepts (problems not necessarily caused by error)
5.2 Examples of Moved Terms
| LLT Name | From PT | To PT |
|---|---|---|
| Accidental dose decrease | Wrong dose | Dosing error |
| Drug maladministration | Product administration error | Product administration issue |
| Expired drug dispensed | Product dispensing error | Product dispensing issue |
| Incorrect storage of drug | Product storage error | Product storage issue |
| Wrong drug product dispensed | Product dispensing error | Product dispensing issue |
Clinical Significance: This reorganization improves the accuracy of medication error coding and analysis, enabling better identification of root causes and prevention strategies. For pharmacovigilance professionals, this means more precise signal detection and risk assessment for medication-related incidents.
6. Proactivity Requests: “Secondary Malignancy” LLT Currency Changes
A proactivity request from a MedDRA user led to a significant review of terms containing “secondary malignancy” .
6.1 The Clinical Problem
| Historical Usage | Contemporary Usage |
|---|---|
| “Secondary malignancy” used as synonym for metastases | Increasingly refers to a new, distinct primary cancer unrelated to previous diagnosis |
The Ambiguity: Equating metastases with a further primary cancer can lead to diagnostic and therapeutic misunderstandings. This shift in usage reflects a need for greater clinical precision .
6.2 Action Taken
A total of 24 “secondary malignancy” LLTs in the context of “metastasis” PTs were changed to non-current status.
6.3 Examples of Changed Terms
| LLT Name | Previous Currency | New Currency | Linked PT Name |
|---|---|---|---|
| Brain secondaries | Current | Non-current | Metastases to central nervous system |
| Secondary carcinoma | Current | Non-current | Metastasis |
| Secondary malignant neoplasm of lung | Current | Non-current | Metastases to lung |
| Secondary malignant neoplasm of skin | Current | Non-current | Metastases to skin |
Pharmacovigilance Implication: Users must now use more precise terms for metastatic disease. For new primary malignancies, appropriate PTs under SOC Neoplasms benign, malignant and unspecified should be selected.
7. Renamed Terms: Ensuring Accuracy and Consistency
Eight English terms were renamed in Version 29.0 to correct spelling, capitalization, spacing, or punctuation .
7.1 Key Renamed Terms
| Code | Version 28.1 Term Name | Version 29.0 Term Name | Level |
|---|---|---|---|
| 10092556 | Intraventricular septum leftward shift | Interventricular septum leftward shift | PT |
| 10085549 | Parainfluenzae viral bronchitis | Parainfluenza viral bronchitis | PT |
| 10033796 | Parainfluenzae viral infections | Parainfluenza viral infections | HLT |
| 10033797 | Parainfluenzae viral laryngotracheobronchitis | Parainfluenza viral laryngotracheobronchitis | PT |
| 10061907 | Parainfluenzae virus infection | Parainfluenza virus infection | PT |
| 10049650 | Parainfluenzae virus infection NOS | Parainfluenza virus infection NOS | LLT |
| 10035727 | Pneumonia parainfluenzae viral | Pneumonia parainfluenza viral | PT |
| 10092783 | Videothoracoscopy | Videothoracoscopy | LLT |
Note: Six terms with “Parainfluenzae” were renamed to “Parainfluenza” to update spelling. While the rename of HLT Parainfluenzae viral infections is technically a complex change, the MSSO opted not to include this minor modification in the complex change proposal list .
8. LLT Currency Status Changes
Thirty-five Lowest Level Terms had changes in currency status in Version 29.0 .
8.1 Categories of Changes
| Category | Examples | Rationale |
|---|---|---|
| Bacterial species names | Brucella abortus, Brucella canis, Brucella melitensis, Brucella suis | Unqualified bacterial names changed to non-current; infection-specific terms exist (e.g., LLT Brucella canis infection added) |
| Ambiguous concepts | Cough decreased, Painful letdown | Descriptors of severity/course not typically included; ambiguity resolved with new terms (e.g., LLT Painful milk letdown) |
| Population/epidemiology qualifiers | Influenza (epidemic) | Population qualifiers usually not added to MedDRA |
| Misspellings | Pyoderma gangenosum | Concept represented by correctly spelled LLT Pyoderma gangrenosum |
| “Secondary malignancy” terms | 24 LLTs (see Section 6) | Ambiguity between metastases and new primary malignancies |
| Stigma-related terms | Risk of stigmatisation (British and US spellings) | Confusion with new PT Concern of disease stigma |
| Manufacturing process terms | Manufacturing process control procedure media fill issue | Imprecise; substituted with new LLT Media fill issue under new PT Aseptic process simulation issue |
8.2 Selected Examples with Rationale
| Lowest Level Term | New Currency | Rationale |
|---|---|---|
| Brucella abortus | Non-current | Represents only bacterium name, not infection |
| Cough decreased | Non-current | Describes change in symptom severity, not typically included |
| Influenza (epidemic) | Non-current | Population qualifier not usually added |
| Painful letdown | Non-current | Ambiguous; replaced by LLT Painful milk letdown |
| Pyoderma gangenosum | Non-current | Misspelling; correct term is Pyoderma gangrenosum |
| Risk of stigmatisation | Non-current | Confusion with new PT Concern of disease stigma |
9. New MedDRA Translations
9.1 Danish Translation Released
The MSSO expects to release Danish after deployment of MedDRA 29.0 translations on 15 March 2026. Danish is part of the 17 European Economic Area (EEA) official languages approved for translation in 2020 to support the electronic product information initiative .
Current Language Status:
- With Danish release: 28 MedDRA languages available
- EEA translations in development: Bulgarian, Maltese, Romanian
- Newly approved translation in development: Uzbek (ICH approved)
Important Note: The EEA translation initiative includes MedDRA terms only and does not include MedDRA user documentation.
10. Technical Updates: APIs and Data Formatting
10.1 MedDRA Download API
In October 2025, the MSSO released a new Download API providing an additional method to obtain MedDRA data files .
Key Features:
| Feature | Description |
|---|---|
| File availability | All versions and supported languages |
| Formats | JSON and dollar sign (‘$’) delimited ASCII (same as current ZIP download) |
| Mappings available | SNOMED CT → MedDRA, MedDRA → SNOMED CT, ICD-10 → MedDRA |
Current download method via ZIP files remains supported.
10.2 Enhancements to Existing APIs
| API | Enhancement |
|---|---|
| Details API | Option to include mapping information in term details |
| Type API | – “Stacked view” for multi-language browsing – Export SMQ and underlying PTs – “Research bin” functionality to export terms |
These enhancements will be available in the GxP-assessed Production environment in the first half of 2026.
10.3 Replacement of Nonbreaking Spaces
The MSSO identified and replaced nonbreaking spaces with standard spaces in certain supported languages (excluding English) starting with Version 29.0 .
Impact: Nonbreaking spaces are visually indistinguishable from standard spaces; changes shown in sequence files may appear as if no modification occurred. This change maintains consistency across all supported translations.
11. Summary of Impact on MedDRA Files
11.1 Term Counts by SOC (Selected Examples)
| SOC | LLTs (Primary) | PTs (Primary) | HLTs | HLGTs |
|---|---|---|---|---|
| Blood and lymphatic system disorders | 1,303 | 345 | 87 | 7 |
| Cardiac disorders | 1,665 | 412 | 74 | 10 |
| Congenital, familial and genetic disorders | 4,824 | 1,953 | 100 | 19 |
| Infections and infestations | 7,989 | 2,256 | 150 | 12 |
| Injury, poisoning and procedural complications | 7,553 | 1,466 | 79 | 9 |
| Investigations | 15,675 | 6,573 | 106 | 23 |
| Neoplasms (benign, malignant, unspecified) | 9,308 | 2,189 | 201 | 39 |
| Nervous system disorders | 4,298 | 1,181 | 108 | 20 |
| Psychiatric disorders | 2,546 | 588 | 77 | 23 |
| Surgical and medical procedures | 6,637 | 2,693 | 141 | 19 |
11.2 Files with Changes
| File Name | Records in V28.1 | Records in V29.0 | Change |
|---|---|---|---|
| hlt_pt.asc | 39,916 | 40,213 | +297 |
| ltt.asc | 90,471 | 91,082 | +611 |
| meddra_history_english.asc | 141,148 | 142,087 | +939 |
| mdhier.asc | 42,221 | 42,530 | +309 |
| pt.asc | 27,163 | 27,361 | +198 |
| smq_content.asc | 97,480 | 98,140 | +660 |
12. Practical Guidance for MedDRA Users
12.1 Preparing for Version 29.0 Implementation
| Action | Tool/Method |
|---|---|
| Review changes in your therapeutic area | MedDRA Version Analysis Tool (MVAT) – compares any two versions |
| Identify new terms relevant to your products | Version Report (included in download) |
| Understand SMQ modifications | MVAT; SMQ documentation |
| Update coding databases and dictionaries | Download API or ZIP files |
| Train coding and safety staff | This article; MSSO documentation |
| Assess impact on legacy data | Consider recoding if necessary for analysis |
12.2 Key Resources
| Resource | Purpose |
|---|---|
| MVAT (MedDRA Version Analysis Tool) | Compare versions; identify specific changes |
| WebCR | Review all change requests from V5.1 to present |
| MedDRA Web-Based Browser | View supplemental changes before next release |
| Weekly supplemental update files | Identify approved changes for next version |
| MSSO Help Desk (mssohelp@meddra.org) | Technical support and questions |
13. Conclusion: The Evolving Language of Drug Safety
MedDRA Version 29.0 represents another step forward in the ongoing effort to maintain a medical terminology that is precise, comprehensive, and reflective of current clinical practice and scientific understanding.
Key takeaways from this release:
- Increased granularity: 198 new PTs and 611 new LLTs enhance coding precision
- Improved medication error classification: Reorganized terms distinguish between “errors” and “issues”
- Clinical accuracy: “Secondary malignancy” terms updated to reflect modern usage
- Global accessibility: Danish translation added; Uzbek in development
- Technical innovation: New Download API and enhanced existing APIs facilitate data integration
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 29.0 ensures that the global pharmacovigilance community has the vocabulary needed to protect patient safety in an era of rapid therapeutic innovation.
