FDA Adverse Event Reporting System (FAERS)

Key facts

Maintained by

U.S. Food and Drug Administration

Report sources

Manufacturers (mandatory); health professionals and consumers (voluntary)

Coding

Events coded in MedDRA; report structure follows ICH E2B

Public access

FAERS Public Dashboard and quarterly data extract files

Predecessor

Replaced the legacy Adverse Event Reporting System (AERS) in 2012

What is FAERS?

FAERS collects reports of suspected adverse events after a drug or therapeutic biologic reaches the market. Manufacturers must submit the reports they receive, and health care professionals, patients and caregivers can report directly to the Food and Drug Administration (FDA) through MedWatch.

FDA safety evaluators review the reports for new safety signals, such as an unexpected adverse event or a known event reported more often or more severely than expected. A signal can lead to further study, a Drug Safety Communication, a labeling change and, in rare cases, removal from the market.

FAERS does not cover vaccines, which are reported to the Vaccine Adverse Event Reporting System (VAERS), or medical devices, which are reported to the MAUDE database.

How FAERS data is structured

Each report is a case about one patient and can name several drugs and several reactions. The quarterly extract files are organized as linked tables:

Follow-up information creates a new version of the same case, so analyses should keep only the latest version of each case and remove duplicates.

• Demographics: case and version identifiers, report dates, patient age and sex, and reporter type and country.
• Drug: each product named, its role (primary suspect, secondary suspect, concomitant or interacting), route and dose.
• Reaction: adverse events coded as MedDRA preferred terms.
• Outcome: seriousness outcomes such as death, hospitalization or disability.
• Indication and therapy: why each drug was taken and when therapy started and stopped.

Why FAERS matters

FAERS is the largest public source of postmarketing drug safety reports in the United States:

• Signal detection: disproportionality methods compare how often an event is reported for one drug with how often it is reported for all others.
• Competitive safety profiles: medical affairs and market access teams compare reporting patterns across drugs in a class.
• Regulatory watch: FDA publishes quarterly lists of potential signals of serious risks identified from FAERS, which can precede labeling changes.

Limitations of FAERS data

A FAERS report does not establish that a drug caused the event. FDA does not require proof of causation for a report to be submitted, and many reports lack details such as dose, timing or medical history.

FAERS cannot be used to calculate how often an event occurs, because not every event is reported and the number of patients exposed is unknown. Reporting also rises after publicity, new warnings and litigation, so report counts should not be read as event rates or as a ranking of drug safety.