Frequently Asked Questions

Common questions about PillSignal, the FDA's FAERS database, and how to interpret adverse event data.

• What is FAERS?

  FAERS (the FDA Adverse Event Reporting System) is a database maintained by the U.S. Food and Drug Administration that collects reports of adverse events and medication errors for approved drugs and therapeutic biologics. Reports are submitted voluntarily by patients, healthcare providers, and manufacturers. The FDA uses this data to monitor drug safety after products reach the market.

• What is an adverse event?

  An adverse event is any undesirable experience associated with the use of a medical product. This includes side effects, injury, or any other negative outcome that occurs while a patient is taking a medication — whether or not the medication actually caused it.

• Does a report mean the drug caused the adverse event?

  No. A FAERS report documents that an adverse event occurred while a patient was taking a medication, but it does not prove the medication caused the event. Many factors can contribute to a patient's experience, including other medications, underlying health conditions, lifestyle factors, and individual biology. Only controlled clinical studies can establish causation.

• Why does one drug have more reports than another?

  The number of adverse event reports for a drug is influenced by many factors beyond safety, including how widely the drug is prescribed, how long it has been on the market, media attention, and regulatory requirements for manufacturer reporting. A drug with more reports is not necessarily more dangerous than one with fewer reports. Comparing raw report counts between drugs is not a valid measure of relative safety.

• How often is PillSignal's data updated?

  PillSignal's data is refreshed periodically from the OpenFDA API, which itself is updated quarterly by the FDA. The data may lag the most recent reports by approximately three months.

• Can I use PillSignal to decide whether to take a medication?

  No. PillSignal is an informational tool that presents publicly available FDA data. It is not a substitute for professional medical advice. Decisions about starting, stopping, or changing medications should always be made in consultation with a qualified healthcare provider who understands your individual health situation.

• Who created PillSignal?

  PillSignal is an independent project built by a small team. It is not affiliated with the FDA, any pharmaceutical company, or any healthcare organization. For questions or feedback, contact [email protected].

• Is PillSignal free?

  Yes. PillSignal is completely free to use. The site is supported by display advertising.

• Where can I report an adverse event to the FDA?

  You can report adverse events directly to the FDA through their MedWatch program. Reporting helps improve drug safety monitoring for everyone.

• What do the charts on each drug page show?

  Each drug page includes several visualizations of FAERS data: the most frequently reported adverse events, a breakdown of reports by patient sex and age group, the severity of reported outcomes (such as hospitalization or death), and the trend of report volume over time. All charts reflect aggregated data from voluntary reports and should be interpreted with the limitations of FAERS in mind.