The FDA relies on the Adverse Event Reporting system to flag safety issues and identify pharmaceuticals or therapeutic biological products (such as blood products), for further epidemiological study. It may ultimately prompt regulatory responses such as drug labeling changes, letters to health care professionals, or market withdrawals.
The agency requires product manufacturers and distributors to report adverse events regularly in accordance with 21 CFR 310.305 and 314.80. Mandatory reports for drugs in clinical trials and newly marketed drugs are submitted in various forms: 15-day alerts, quarterly or annual updates. The MedWatch program also collects voluntary reports from health care professionals and consumers. Adverse drug experiences include any serious and unexpected consequences of human drug use in a medical practice - such as failure of "expected pharmacological action," as well as accidental or intentional overdoses or abuse.

AERS replaced the Spontaneous Reporting System in October 1997. The FDA estimates that 118 reports for 1997-98 are included in the old SRS data. The AERS collection begins with the fourth quarter of 1997 and is complete through December 2006. Emphasis on reporting and efficiency of collecting reports have fluctuated, as seen by the relatively small number of records for the earlier years in this dataset and the incomplete entries throughout.

The AERS format attempts to improve and standardize the same basic information fields collected in SRS. The most notable difference between the two sets is a Comments table containing detailed memo fields; it only exists for SRS data 1993-1998.