Differences in Adverse Events Reporting Between Natural Products Versus Prescription Products in the United States and Canada

OBJECTIVES: Natural dietary supplement sales saw a 17% increase in 2020 from the year prior. However, it is well established that these products present risks of adverse events. Considering the lack of requirements by regulatory bodies in the United States and Canada for reporting adverse events, the quality, volume, and sources of reports may vary compared to prescription medications. The aim of this study is to examine adverse event reporting patterns in both the Unites States and Canada, comparing top-selling natural products with top-selling prescription medications.

METHODS: The 50 most commonly prescribed medications were compiled from an annual medical expenditure survey conducted by the United States government. The 50 most commonly purchased natural products were compiled from a 2020 market report conducted by the American Botanical Council. Individual spontaneous case reports mentioning these products were identified from 10 years of data (March 2011-March 2021) from the FDA Adverse Event Reporting System (FAERS) and the Canada Vigilance Adverse Reaction Online Database (CVAR). SQL was used to conduct descriptive analysis.

RESULTS: A total of 1,132 reports for natural products as the suspected contributing agent were received in CVAR with 6,857 related adverse events. For prescription products, 53,164 reports were received by CVAR related to 710,378 adverse events. Approximately 77% of natural product and 70% of prescription drug reports were considered serious adverse events. The missing data for outcome of natural product reports was 60.2% vs 52.2% for prescription medications, questioning the quality of reports for both product types. Reporters varied for natural products and prescription drugs with 5.4% and 2.7% reports received from hospitals, respectively.

CONCLUSIONS: Variation in adverse event reporting in CVAR between natural products and prescription medications highlights that pharmacovigilance studies should not include combined summative data for these products. FAERS data are still under review as work in progress.