Background/Objectives: While breastfeeding is highly recommended, breastfed infants may be exposed to drugs by milk due to maternal pharmacotherapy, resulting in a risk of adverse drug events (ADE) or reactions (ADRs). The U.S. Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) is an online pharmacovigilance database, while the Drugs and Lactation Database (LactMed®) includes accurate and evidence-based information on levels of substances in breast milk and infant blood, and possible ADRs in nursing infants. We aimed to explore the FAERS database and compare ADE/ADR information patterns between both databases. Methods: The FAERS database was explored (29 July 2024) for ADEs related to drug exposure during lactation to determine annual trends, infant outcomes, and regions of reporting. The active pharmaceutical ingredients (APIs) associated with these ADEs were categorized based on the Anatomical Therapeutic Chemical (ATC, first level) classification. The top five APIs in each ATC group were explored in terms of the type of ADEs reported and compared to information in LactMed®. Results: In total, 2628 ADEs were obtained from the FAERS database, with increased reporting over time. In the FAERS database, 68.4% of the patients were under 2 months old, 5.5% had life threatening ADEs, and 3.6% died, while 84.70% of the cases were categorized as serious. Most ADEs were from North America (44.9%). Most drugs (50.9%) were nervous system drugs. The most frequent reported outcome was “other outcomes (without additional subdivision or information)” (58.2%), reflecting the diversity in outcomes reported. When related to the same drug, the FAERS database and LactMed® resource exhibited both similarities and differences in the types of reported ADE/ADR. Conclusions: The FAERS database is a useful tool to detect potential ADEs (rather sensitive), without ADR assessment, while LactMed® provides guidance driven by relevant ADRs (rather specific). The FAERS database is useful to obtain exploratory information about ADEs during lactation to increase the knowledge about drug safety during breastfeeding and the awareness of the possible risks in nursing infants, while LactMed® translates all available information into guidance.
