Understanding What is MedDRA in Pharmacovigilance?

October 6, 2025 •

3 min read

Used by nearly 7,500 organizations in almost 130 countries, the Medical Dictionary for Regulatory Activities (MedDRA) is the international standard for coding medical information. This critical tool defines what is MedDRA in pharmacovigilance and ensures a consistent language for safety data reporting and analysis globally. By standardizing terminology, MedDRA facilitates the exchange of regulatory information among health authorities, pharmaceutical companies, and other stakeholders.

Quick Summary

MedDRA is a standardized medical terminology for classifying adverse event data. Its hierarchical structure enables consistent reporting, effective signal detection, and global data exchange throughout a medical product's lifecycle, supporting patient safety and regulatory compliance.

Key Points

Standardized Terminology: MedDRA provides a common, internationally accepted vocabulary for medical information, essential for consistent reporting across different regions.
Hierarchical Structure: Its five-level hierarchy, from the most specific Lowest Level Terms (LLTs) to the broadest System Organ Class (SOC), allows for both detailed coding and comprehensive data analysis.
Critical for Pharmacovigilance: It is the foundation for coding adverse event reports and detecting safety signals globally, supporting regulatory compliance and public health.
Facilitates Data Analysis: Features like Standardized MedDRA Queries (SMQs) enable efficient retrieval and analysis of data related to specific medical conditions.
Continuously Maintained: The Maintenance and Support Services Organization (MSSO) and ICH oversee biannual updates, ensuring the terminology remains current with medical knowledge.
Enables International Collaboration: MedDRA's worldwide acceptance simplifies the exchange of safety data between regulatory agencies and pharmaceutical companies globally.

The Core Purpose of MedDRA

Before the creation of MedDRA, various terminologies like COSTART and WHO-ART were used for safety reporting, leading to inconsistencies in comparing data across regions. The International Council for Harmonisation (ICH) developed MedDRA as a highly specific and standardized medical terminology to address this.

MedDRA's main goal is to enable the sharing of regulatory information for medical products from clinical trials through post-marketing surveillance. It encompasses a wide range of medical concepts, including symptoms, diagnoses, procedures, and investigations. Regulatory bodies like the FDA and EMA require its use, improving data quality, communication, and the speed of safety signal detection.

The Five-Level Hierarchical Structure

MedDRA is organized into a five-level hierarchy to allow for flexible data use.

Lowest Level Term (LLT): The most specific terms, including synonyms and variations, used for initial data entry. There are over 80,000 LLTs.
Preferred Term (PT): Represents a single medical concept, grouping related LLTs, often used for summaries and analysis.
High Level Term (HLT): Groups related PTs.
High Level Group Term (HLGT): A higher grouping of HLTs.
System Organ Class (SOC): The broadest level, classifying terms by body system or cause. MedDRA's multi-axial nature allows a PT to belong to multiple SOCs for comprehensive data retrieval.

How MedDRA Functions in Pharmacovigilance

In pharmacovigilance, MedDRA codes adverse event reports, converting free text into a structured format. Trained coders map verbatim descriptions to the most specific LLT. This coded data is then stored and analyzed.

Signal Detection and Analysis

MedDRA's structure aids signal detection by grouping related terms to identify patterns indicating potential safety issues. Standardized MedDRA Queries (SMQs) are predefined searches for terms related to specific conditions, helping to find relevant safety cases.

Comparison of MedDRA with Other Terminologies

While MedDRA is key for regulatory pharmacovigilance, other terminologies exist for different uses. The table highlights key distinctions:


Feature	MedDRA	SNOMED CT	CTCAE
Primary Use	Regulatory reporting of adverse events.	Comprehensive terminology for electronic health records.	Grading adverse events in oncology trials.
Ownership/Management	ICH via MSSO.	IHTSDO.	NCI.
Content	Focuses on signs, symptoms, diagnoses for regulatory purposes.	Broad scope of clinical findings, procedures, etc..	Descriptions and grading for cancer treatment related adverse events.
Updates	Biannually (March and September).	Biannually, but implementation varies.	Regularly updated.

Benefits and Challenges of Using MedDRA

MedDRA offers several advantages in pharmacovigilance:

Global Standardization: Ensures consistent safety data reporting and analysis worldwide.
Improved Data Quality: Reduces ambiguity through standardized coding.
Enhanced Signal Detection: The hierarchical structure and SMQs help identify potential safety signals efficiently.
Regulatory Compliance: Its requirement by major regulatory bodies simplifies international reporting.
Facilitated Data Exchange: Allows for seamless sharing of safety data between systems.

However, MedDRA also has challenges:

Coding Complexity: Requires specialized training for accurate coding due to the large number of terms and multi-axial structure.
Version Management: Biannual updates necessitate keeping systems aligned with the latest version.
Interpretation Variation: Potential for inconsistent coding based on coder interpretation of verbatim reports.

Maintenance and Governance of MedDRA

The ICH MedDRA Management Committee oversees MedDRA, while the Maintenance and Support Services Organization (MSSO) manages its daily operations, including development and distribution. The MSSO releases biannual updates to incorporate new medical knowledge. Free training is available to support correct usage.

Conclusion

MedDRA is essential for modern pharmacovigilance, providing a standardized global terminology for adverse event reporting. Its structure supports robust data analysis and signal detection. While coding requires training and version management is necessary, MedDRA significantly improves data quality, regulatory compliance, and international collaboration, ultimately enhancing patient safety.

For more information on MedDRA, visit the official ICH website.

ICH MedDRA Website: https://www.ich.org/page/meddra

Frequently Asked Questions

MedDRA stands for the Medical Dictionary for Regulatory Activities. It is a standardized medical terminology used for regulatory purposes.

MedDRA was developed under the auspices of the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH).

Adverse event reports, initially captured as free text, are coded by trained professionals who map the reported terms to the most specific Lowest Level Term (LLT) in the MedDRA dictionary. This standardized coding is then used for analysis and regulatory reporting.

The highest and broadest level in the MedDRA hierarchy is the System Organ Class (SOC), which classifies terms by body system or etiology.

MedDRA is updated and released biannually, in March and September, by the Maintenance and Support Services Organization (MSSO) to incorporate new terms and changes.

SMQs are structured sets of MedDRA terms that relate to a specific medical condition or area of interest. They are used to facilitate the retrieval and analysis of potentially relevant safety cases from databases.

MedDRA is used by regulatory authorities (like the FDA and EMA), pharmaceutical companies, clinical research organizations, academics, and healthcare professionals globally for safety reporting and analysis.