How to Read Drug Safety Data on This Site

Getting the Most Out of Drug Fact Check

Drug Fact Check presents a lot of data about FDA adverse event reports. If you are not familiar with pharmacovigilance terminology, the numbers and metrics can be confusing. This guide walks you through each section of the site and explains what the data means, how to read it, and what to watch out for.

Understanding Drug Pages

When you visit a drug page — for example, a page for a common medication like metformin or lisinopril — you will see several key sections.

Report Summary Statistics

At the top of each drug page, you will find four summary cards:

• Total Reports — The total number of adverse event reports in the FAERS database that list this drug as a suspect or concomitant medication. A “suspect” drug is one the reporter believes may have caused the adverse event. A “concomitant” drug is one the patient was also taking at the time.

• Serious Reports — The subset of total reports that were classified as “serious.” The FDA defines a serious adverse event as one that results in death, hospitalization, disability, a life-threatening situation, a congenital anomaly, or requires medical intervention to prevent one of these outcomes.

• Death Reports — The number of reports where the outcome was listed as death. This is a subset of serious reports. It is critical to understand that this number does not mean the drug killed these patients. The patient may have died from their underlying disease, another medication, or an unrelated cause.

• Reported Reactions — The number of distinct adverse event terms (MedDRA Preferred Terms) that appear across all reports for this drug. A drug with 200 reported reactions means 200 different types of adverse events have been mentioned in its reports.

Death Report Ratio

Below the summary cards, you will see a death report ratio displayed as a percentage with a color-coded badge:

• Low (green) — Death ratio below 1% of total reports
• Moderate (yellow) — Death ratio between 1% and 5%
• High (red) — Death ratio above 5%

This metric provides context for the death count. A drug with 100 death reports out of 100,000 total reports (0.1%) has a very different profile than a drug with 100 death reports out of 500 total reports (20%). The latter likely treats a very serious or terminal condition.

Keep in mind that a high death ratio does not mean the drug is dangerous. Chemotherapy drugs, for instance, typically have high death ratios because cancer patients have elevated mortality regardless of treatment.

Patient Demographics

When available, drug pages show a breakdown of reports by patient sex. This section displays the number of reports from male and female patients as a visual bar chart. Not all reports include demographic data, so these numbers will typically be less than the total report count.

Demographic data can reveal interesting patterns — some drugs show significantly more reports from one sex, which may reflect prescribing patterns, biological differences in drug response, or differences in reporting behavior.

Reported Adverse Reactions Table

The main data table on each drug page lists every adverse event term that has been reported for the drug, sorted by frequency. For each reaction, you will see:

• Reaction name — The MedDRA Preferred Term. Click it to visit the reaction page for that term.
• Reports — How many reports for this drug mentioned this reaction. Note that a single report can list multiple reactions.
• % of Total — The percentage of total reaction mentions accounted for by this specific reaction. This helps you understand relative frequency.

The most commonly reported reactions for most drugs are general terms like “drug ineffective,” “nausea,” “headache,” “fatigue,” and “pain.” These reflect both genuine side effects and the general nature of complaints patients and doctors tend to report.

Understanding Reaction Pages

Reaction pages flip the perspective. Instead of showing all reactions for one drug, they show all drugs associated with a particular reaction.

The summary cards show:

• Total Reports — How many FAERS reports across all drugs mention this reaction
• Drugs Involved — How many different drugs have been associated with this reaction
• Most Reported Drug — The single drug with the most reports for this reaction

The data table lists each drug associated with the reaction, sorted by report count. The percentage column shows what share of total reports for this reaction involves each drug.

A drug appearing at the top of a reaction page does not mean it is the most likely cause of that reaction. It may simply be the most widely prescribed drug among those associated with the reaction. For example, metformin might top the list for “nausea” not because it causes the most nausea, but because it is one of the most prescribed drugs in the world.

Understanding Drug Class Pages

Drug class pages group drugs by their therapeutic classification (Established Pharmacologic Class or EPC). These pages show aggregate statistics across all drugs in the class and let you compare individual drugs within the same category.

This can be useful for understanding whether a particular adverse event pattern is specific to one drug or common across an entire drug class. If all drugs in a class show similar reaction profiles, the adverse events may be related to the mechanism of action rather than a specific formulation.

Tips for Responsible Data Interpretation

Compare drugs of similar use

Comparing a blood pressure medication to a chemotherapy drug is not meaningful. When evaluating a drug’s safety profile, compare it to other drugs used for the same condition.

Consider the denominator

A drug with 50,000 reports that is taken by 30 million Americans annually has a very different risk profile than a drug with 50,000 reports taken by 100,000 patients. Unfortunately, FAERS does not include prescription volume data, so this context must come from other sources.

Look at report proportions, not just counts

The percentage column in reaction tables is often more informative than raw counts. If “nausea” accounts for 15% of a drug’s reaction reports versus 2% for another drug in the same class, that relative difference may be meaningful even if the raw numbers are similar.

Do not self-diagnose or self-treat

The data on this site is meant to inform, not to replace medical advice. If you are concerned about a medication you are taking, bring your concerns to your healthcare provider. They can evaluate your specific situation, consider your full medical history, and recommend appropriate next steps.

Check the drug label

The FDA-approved drug label (package insert) contains the most authoritative information about a drug’s known side effects, including incidence rates from clinical trials. You can find drug labels at DailyMed or Drugs@FDA.

A Note on Data Currency

The data on Drug Fact Check is periodically updated from the openFDA API. There may be a delay between when new reports are submitted to the FDA and when they appear on this site. For the most current data, you can query the openFDA API directly.

This guide is for informational purposes only and does not constitute medical advice.