Underreporting of Adverse Drug Reactions: Why Healthcare Professionals Don’t Report

Discover why healthcare professionals may not report suspected ADRs and how reducing reporting barriers can strengthen pharmacovigilance.

Intro

Spontaneous ADR reports are a valuable source of post-marketing safety information, but their usefulness depends on suspected reactions being recognised and reported. Health care professionals are often in the best position to identify possible reactions during routine clinical practice, yet reporting must compete with patient care, documentation, and other clinical responsibilities.

This creates several barriers to pharmacovigilance. Time pressure can make reporting feel like an additional administrative task, while uncertainty about whether a medicine caused an event may discourage submission. Complex adverse drug reaction reporting procedures and limited feedback can create further friction. As a result, underreporting of adverse drug reactions may leave PV teams and regulators with a less complete picture of real-world medicine safety. Addressing ADR underreporting, therefore, requires more than encouraging professionals to report; it also means making reporting clearer, easier, and better integrated into clinical workflows.

What Is ADR Underreporting?

ADR underreporting occurs when a suspected adverse drug reaction is not formally submitted through an appropriate pharmacovigilance reporting channel. The scale of the problem can be substantial. A systematic review of 37 studies found a median underreporting rate of 94%, although estimates varied considerably between settings and types of reactions.

Several steps should be distinguished. ADR occurrence refers to the clinical event experienced by a patient after taking a medicine. Recognition occurs when a healthcare professional identifies that the event could be related to the medicine. Documentation in a medical record means recording the reaction and relevant clinical information as part of patient care. Formal pharmacovigilance reporting, in contrast, means submitting the suspected reaction through a designated spontaneous reporting system so it can be assessed alongside other safety information.

These steps do not always happen together. A reaction may be recognised and documented without being formally reported, meaning that an event can enter clinical records without reaching the wider safety database.

Why Does ADR Underreporting Matter for Pharmacovigilance?

Underreporting affects the entire safety data flow, from the initial clinical observation to regulatory decision-making. When a suspected reaction is not submitted, it is missing from spontaneous reporting databases, reducing the completeness of the available evidence. This can limit the visibility of rare or unexpected reactions and make it harder to identify patterns across individual cases.

Over time, fewer reports may also affect signal detection, particularly when a potential safety issue is uncommon or presents differently from established risks. Incomplete reporting can complicate the characterisation of known risks and may influence the prioritisation of further investigation. These are among the broader pharmacovigilance challenges that can affect the ability of safety teams to build a complete picture of medicine-related risks.

Spontaneous reports are only one source of evidence, but each well-documented report can add valuable clinical context when combined with information from other cases and data sources. Together, these contributions support better safety decisions and ultimately help with protecting public health.

Why Do Healthcare Professionals Underreport Adverse Drug Reactions?

Underreporting rarely has a single cause. A healthcare professional’s decision to report can be shaped by workload, knowledge, perception of responsibility, uncertainty about the suspected reaction, and the complexity of the reporting process. The organisational environment also matters: reporting may be easier when clear procedures, accessible systems, and a positive reporting culture support it. These associated factors often overlap, meaning that even professionals who understand the importance of medication safety may not report consistently when reporting competes with clinical priorities or feels difficult to complete.

Lack of Time and Competing Clinical Priorities

For most health professionals, patient care naturally takes priority over additional administrative tasks. During busy shifts, high patient volumes, and periods of increased clinical demand, reporting a suspected ADR may be postponed even when the reaction is considered important.

Unlike an immediate clinical decision, reporting ADRs is often perceived as a task that can be completed later. It may require reviewing the patient’s history, identifying the suspected medicine, documenting the reaction, and collecting additional case information. This can add to an already substantial administrative workload.

The problem is not necessarily a lack of interest in medication safety. Rather, reporting may compete directly with activities that have an immediate impact on patient care. When reporting requires leaving the usual clinical workflow or completing a separate form, even a motivated professional may delay submission. Simplifying the process and integrating it into routine practice can help reduce this practical barrier.

Uncertainty About Causality

One of the biggest barriers to reporting is uncertainty about causality: Was it really the drug? In routine practice, patients may have comorbidities, polypharmacy, an underlying disease, or concurrent treatment that could explain the event. Some reactions may also be delayed, making the relationship between exposure to the medicine and the event less obvious.

This uncertainty can lead an HCP to wait for stronger evidence before submitting a report. However, a suspected ADR does not require definitive proof of causality to be reported. The purpose of spontaneous reporting is to collect clinical suspicions that can later be assessed alongside other safety information.

Healthcare professionals should therefore provide the available clinical information rather than delay reporting until the medicine-event relationship is certain. Pharmacovigilance teams can perform further medical review, follow-up, and causality assessment after receiving the initial report.

Uncertainty About What Should Be Reported

Another barrier is uncertainty about which events are worth reporting. Some healthcare professionals may assume they should report only serious adverse drug reactions, report only unexpected reactions, or that known reactions do not matter. Others may think that another professional will probably report the case, or that a single report cannot make a difference.

These assumptions can contribute to underreporting reasons, particularly when reporting criteria are not clearly understood. In the EU, reporting arrangements are implemented through national systems rather than through a universal procedure for all HCPs. The EU pharmacovigilance framework supports reporting of suspected adverse reactions through these national systems, while the European Medicines Agency and national competent authorities encourage healthcare professionals and patients to do so.

The key point is that uncertainty about whether a reaction is worth reporting should not automatically prevent a suspected ADR from reaching the appropriate reporting system.

Lack of Knowledge or Training

Healthcare professionals’ knowledge of reporting procedures can influence whether suspected ADRs are recognised and submitted. They may be unfamiliar with available reporting channels, uncertain about the required information, or unaware of how their national reporting systems work. Insufficient pharmacovigilance training can reinforce these gaps, particularly when reporting is not regularly covered in clinical education or workplace onboarding.

However, the issue is not necessarily a lack of professional competence. In many cases, reporting is insufficiently integrated into the routine clinical workflow. A healthcare professional may understand the importance of medication safety but still hesitate because they are unsure where to report, what information to provide, or what happens after submission.

Practical educational programs, short reporting scenarios, quick-reference guidance, and periodic refreshers can help address these barriers without adding significant administrative burden to already busy clinical teams.

Complex or Fragmented Reporting Processes

Even when healthcare professionals understand why reporting matters, a complicated reporting system can discourage them from submitting a case. Separate reporting portals, lengthy forms, repetitive data entry, and uncertainty about which fields are mandatory can turn a relatively simple task into an additional administrative burden.

The problem becomes greater when reporting systems sit outside the normal clinical workflow. A professional may need to leave the electronic health record, search for information in another system, and manually enter data that has already been documented. A lack of integration with electronic records can therefore create unnecessary duplication and increase the time needed to submit a report.

These practical barriers can affect the reporting of adverse drug events even when the suspected reaction is clinically relevant. Improving the user experience does not necessarily mean removing important checks. Instead, clearer forms, fewer unnecessary steps, appropriate data pre-population, and better system integration can make adverse drug reaction reporting easier while preserving the information needed for pharmacovigilance assessment.

Fear of Making a Mistake or Legal Concerns

Some healthcare professionals may hesitate to report because they worry that an incorrect report could have consequences. They may be uncertain whether the available evidence is sufficient or be concerned about incorrectly assigning causality. This can be particularly relevant when the clinical picture is complex or when several medicines are involved.

Reporting a suspected reaction does not mean stating that a medicine definitely caused it. Clear guidance can help professionals distinguish between communicating a clinical suspicion and making a final causality assessment, reducing unnecessary hesitation while supporting a constructive reporting culture.

Lack of Feedback and Perceived Impact

When healthcare professionals do not see what happens after submission, reporting can feel like an administrative task without a visible clinical outcome. This absence of feedback may reduce awareness of how individual reports contribute to signal detection and lead to a low perceived impact on the individual.

In the EU, reports collected in EudraVigilance are regularly reviewed and analysed by EMA and national competent authorities to identify potential safety signals. The Pharmacovigilance Risk Assessment Committee (PRAC) then evaluates relevant signals and may recommend further investigation or regulatory action, such as changes to the medicine information.

Understanding this process can help healthcare professionals see that a single report is not necessarily an isolated administrative action. Its information can become part of a much larger evidence base used to monitor medicine safety.

What Does the ADR Reporting Process Require From a Healthcare Professional?

For a healthcare professional, reporting a suspected ADR can involve several practical steps: recognising a suspected reaction, identifying the medicine involved, documenting relevant patient and event information, submitting the initial report, and responding to follow-up questions when additional data are required. The process does not require an HCP to prepare a complete regulatory ICSR independently. Once submitted, the case can be reviewed and processed by pharmacovigilance teams.

What Makes a Report Useful?

A useful safety report should contain four core elements:

• Identifiable reporter — someone who can be contacted for clarification or follow-up.
• Identifiable patient — enough information to establish that the report concerns a real patient.
• Suspected medicinal product — the medicine considered potentially associated with the event.
• Suspected adverse reaction — a description of the reaction or clinical event being reported.

Together, these elements provide the basic information needed for a valid ICSR within the EU pharmacovigilance framework.

How Underreporting Creates a Downstream Burden for Pharmacovigilance Teams

Underreporting creates a paradox for pharmacovigilance teams: fewer reports do not necessarily mean less work. When reports are poor, incomplete, or delayed, PV professionals may need to spend more time obtaining and reconciling information later in the safety workflow.

A weak initial report can lead to extensive follow-up, incomplete ICSRs, difficulty assessing causality, fragmented information, weaker signal datasets, and additional reconciliation effort. Missing details may require PV teams to contact the reporter, review other available sources, or compare information across systems before a case can be fully assessed.

The downstream flow can be viewed as:

Clinical event → recognition → initial report → follow-up → case completion → medical review → coding → duplicate management → signal analysis.

A gap at the beginning of this process can create additional work at several later stages. For pharmaceutical companies and other organisations managing large safety databases, efficient ICSR management can help structure incoming information, identify missing data, support follow-up, and maintain consistent case processing.

Reducing reporting barriers therefore benefits not only healthcare professionals but also the PV teams responsible for turning individual reports into usable safety evidence.

How Can the Reporting Burden on Healthcare Professionals Be Reduced?

Make Reporting Easier to Access

Clear reporting routes can remove unnecessary friction from the reporting process. Fewer steps, intuitive digital interfaces, and easy access within routine clinical workflows can make it more practical for healthcare professionals to submit suspected ADRs without adding significant administrative workload.

Reduce Duplicate Data Entry

Integration with existing clinical systems can reduce repetitive data entry where technically and legally feasible. Appropriate pre-population of available information can save time while allowing the healthcare professional to review and confirm the data. The goal is not full automation of HCP reporting but a simpler, more efficient process.

Provide Clear Guidance on What to Report

Clear guidance can reduce uncertainty at the point of reporting. Healthcare professionals should understand that suspicion is sufficient to initiate a report and that certainty of causality is not required. They should also know where to submit the report and which information is most useful for subsequent assessment.

Improve Training Without Adding More Administrative Burden

Training does not need to be lengthy to be effective. Short practical formats can include reporting scenarios, real-world examples, quick-reference instructions, onboarding materials, and periodic refreshers. These approaches can help professionals recognise suspected reactions and understand reporting procedures without creating another significant administrative obligation.

Close the Feedback Loop

Feedback can show healthcare professionals what happens after a report is submitted and how their information contributes to signal detection. Explaining how pharmacovigilance evidence can support product information changes or other regulatory action can make the individual contribution more visible and strengthen motivation to report.

Can Technology and Automation Help Reduce ADR Underreporting?

Technology can help reduce reporting barriers at two levels: the healthcare level and the pharmacovigilance level.

At the healthcare level, digital tools, such as mobile apps, intuitive interfaces, and integration with existing clinical systems, can make reporting easier to access. Where technically and legally feasible, pre-populating available information can reduce repetitive data entry. However, technology should support healthcare professionals rather than replace clinical judgement or fully automate HCP reporting.

At the pharmacovigilance level, automation can help teams process, organise, and assess the safety information they receive. Structured workflows can support case processing, follow-up, data quality checks, and the identification of potential safety information from different sources. This is where pharmacovigilance automation can reduce repetitive work and help PV teams manage safety information more efficiently.

For example, DrugCard provides dedicated solutions for ICSR management and adverse event data management, addressing different stages of the safety workflow. These capabilities can help PV teams organise incoming safety information and reduce manual work without replacing the expert assessment required for individual cases.

An adverse event database can provide a structured environment for managing safety information and supporting downstream assessment. The goal is therefore not simply to collect more reports, but to create a more connected workflow from initial safety information through case processing and further pharmacovigilance assessment.

Why Better ADR Reporting Is About Quality, Not Just Quantity

Better ADR reporting is not simply about increasing the number of cases. The value of a report depends heavily on the information it contains. Relevant clinical details, a clear chronology, the suspected medication, an accurate description of the reaction, and available follow-up data can all help pharmacovigilance teams assess a case more effectively.

Duplicate control is also essential. The same clinical event may be reported through multiple sources, and treating duplicate reports as separate cases can distort the available safety picture. Conversely, a high number of reports without sufficient clinical context can create noise rather than meaningful evidence.

This distinction matters during signal management, where PV teams assess whether patterns across cases may indicate a potential safety concern. A smaller set of well-characterised cases can sometimes provide more useful evidence than a much larger dataset containing incomplete or duplicated information.

The goal, therefore, is not maximum reporting volume. It is timely, relevant, and sufficiently detailed safety information that can support reliable assessment and informed regulatory decisions.

Conclusion

Healthcare professional participation remains crucial to effective pharmacovigilance because clinicians are often the first to recognise suspected safety issues in routine practice. Reducing reporting barriers does not mean simply asking HCPs to submit more cases. Easier reporting processes, clearer guidance, practical training, timely feedback, and efficient downstream PV workflows can help generate more useful safety information without disproportionately increasing administrative burden.

Technology can support this goal by reducing repetitive work and connecting safety information across the workflow. For PV teams, solutions such as DrugCard can help streamline these processes while keeping expert assessment at the centre of medication safety.

Frequently Asked Questions

What is the underreporting of adverse drug reactions?

Underreporting of adverse drug reactions occurs when suspected reactions are not formally submitted through an appropriate pharmacovigilance system, leaving potentially useful safety information outside the available evidence.

Why are adverse drug reactions underreported?

Common reasons include limited time, uncertainty about causality, insufficient training, complex reporting processes, unclear responsibilities, and limited feedback about how individual reports contribute to patient safety.

What percentage of adverse drug reactions are not reported?

There is no universal percentage. A systematic review found a median underreporting rate of 94%, but estimates vary substantially by medicine, reaction, country, healthcare setting, and study methodology.

Do healthcare professionals need to prove that a drug caused an ADR before reporting it?

No. Healthcare professionals can report a suspected ADR without definitive proof of causality. Further assessment can be performed by pharmacovigilance teams using the available clinical information.

How does ADR underreporting affect signal detection?

Underreporting can reduce the amount of available safety information, potentially making rare or emerging patterns harder to identify and assess alongside reports from other sources.

Can patients report adverse drug reactions in the EU?

Yes. Patients can report suspected adverse reactions through applicable national reporting systems in European countries. Patient reporting can contribute to pharmacovigilance alongside reports submitted by healthcare professionals.