A DSUR, or Development Safety Update Report, is an annual safety report that drug sponsors must submit to regulatory agencies for any drug still under clinical investigation. It provides a comprehensive, once-a-year snapshot of all safety information collected across every ongoing trial of that drug, giving regulators the data they need to decide whether a trial should continue, be modified, or be stopped. The DSUR is defined by the ICH E2F guideline, an international standard adopted by the FDA, the European Medicines Agency, and other major regulators worldwide.
Why the DSUR Exists
Before the DSUR became a global standard, different countries required different annual safety reports. In the United States, sponsors filed an IND Annual Report. In the European Union, they submitted an Annual Safety Report. These reports covered similar ground but had different formats and requirements, which meant companies running multinational trials had to prepare multiple documents covering essentially the same data.
The ICH E2F guideline created the DSUR as a single, harmonized format that satisfies both the U.S. and EU requirements simultaneously. A sponsor running trials across dozens of countries can now prepare one core document instead of juggling region-specific versions. Both the FDA and EMA accept the DSUR in place of their older regional reports.
What a DSUR Covers
The DSUR is not a report on a single trial. It pulls together safety data from every active study of a given drug, whether that’s a small Phase 1 dose-finding study or a large Phase 3 efficacy trial. The goal is to give regulators an aggregate picture: across all the people who have received this experimental drug over the past year, what safety signals are emerging?
The core of the report is an analysis of serious adverse reactions, meaning harmful events that are both serious (resulting in hospitalization, disability, or death) and reasonably linked to the drug. Sponsors compile cumulative summary tables of these events, covering not just the current reporting period but the entire development history of the drug. This lets regulators see whether a particular safety concern is growing over time or was a one-off event.
Beyond adverse reactions, the DSUR also includes a list of subjects who died during the reporting period, a list of participants who dropped out of trials because of adverse events, any significant changes to study protocols or manufacturing processes, and an overall assessment of whether the drug’s known risks have changed since the last report. The sponsor is expected to interpret the data, not just present it. The report concludes with the sponsor’s judgment on whether the benefit-risk balance still supports continuing development.
Region-Specific Requirements
While the DSUR is a global standard, regulators in different countries can request additional information through a dedicated section of the report. The FDA, for example, may require sponsors to include significant Phase 1 protocol modifications that weren’t previously submitted, a description of the general investigation plan for the coming year, and a log of outstanding regulatory business related to the U.S. IND application. These region-specific additions are typically included as appendices so the core report stays consistent across jurisdictions.
Submission Timeline
DSURs are submitted annually. The reporting cycle is anchored to a date called the Development International Birth Date, or DIBD, which is typically the date the drug was first authorized for clinical investigation anywhere in the world. Each year, the sponsor locks the safety data on the anniversary of that date and then has a defined window to compile and submit the report. This annual rhythm continues for as long as the drug remains under active clinical investigation, including marketed drugs that are being studied for new uses.
How DSURs Differ From Post-Market Safety Reports
The DSUR applies specifically to drugs in development, meaning drugs that have not yet been approved or drugs that are approved but being tested for a new indication or population. Once a drug receives full marketing authorization, a different set of periodic safety reports takes over. In the U.S., sponsors submit Periodic Adverse Drug Experience Reports (PADERs). Internationally, the equivalent is the Periodic Benefit-Risk Evaluation Report, or PBRER, which replaced the older Periodic Safety Update Report (PSUR).
The key distinction is the stage of the drug’s lifecycle. A DSUR is built around investigational data from controlled clinical trials, where the sponsor knows exactly how many people received the drug, at what dose, and for how long. Post-market reports like the PBRER deal with a much messier data landscape: spontaneous reports from doctors and patients, post-marketing surveillance studies, and real-world use patterns where dosing and compliance are far less controlled. The analytical approach in each report reflects that difference.
Who Prepares the DSUR
The drug sponsor is responsible for preparing and submitting the DSUR. In practice, this means the company’s pharmacovigilance and regulatory affairs teams work together to collect adverse event data from all ongoing trials, analyze it for emerging safety signals, and draft the narrative sections that interpret what the data means. For large drug development programs with dozens of concurrent studies across multiple countries, assembling a single coherent DSUR is a significant undertaking that typically begins months before the data lock date.
The finished report goes to every regulatory authority that has authorized clinical trials of the drug. It also often goes to ethics committees and data safety monitoring boards overseeing individual studies, giving them the broader safety context they need to protect trial participants.