Harmful or unintended medical outcome occurring during or after treatment
An adverse event is any harmful or unintended medical occurrence in a patient or clinical trial subject who has received a pharmaceutical product or medical treatment. Adverse events range from minor side effects to serious injury or death. The monitoring, reporting, and investigation of adverse events — pharmacovigilance — is fundamental to drug safety, and its failure is central to numerous pharmaceutical scandals.
The FDA's Adverse Event Reporting System (FAERS) collects voluntary reports from healthcare professionals and consumers. However, studies consistently estimate that only 1-10% of adverse events are actually reported, creating a massive blind spot in drug safety monitoring. This underreporting is not accidental — pharmaceutical companies have been documented suppressing adverse event data, manipulating clinical trial results, and pressuring researchers to minimize negative findings.
High-profile examples include Merck's suppression of cardiovascular risks associated with Vioxx, which contributed to an estimated 88,000-140,000 excess cases of heart disease. Internal Merck documents revealed that the company was aware of the risks years before withdrawing the drug. Similar patterns of adverse event suppression have been documented for numerous other medications, demonstrating that the system designed to protect patients is only as reliable as the honesty of those reporting into it.
