EudraVigilance insights: Suspected adverse drug reactions in infants through breastfeeding

We aimed to describe suspected adverse drug reactions (ADRs) in infants resulting from medications transmitted through mothers' milk, as reported to the European ADR database, EudraVigilance. The research sought to understand the frequency, seriousness and nature of these ADRs to assess potential risks associated with maternal medication use during breastfeeding.

Data from EudraVigilance were analysed. The study included all reported ADRs suspected to be related to medications transmitted through mothers' milk from 1 January 2013 to 1 July 2023. The data were categorized by reporting time, infant age and sex, seriousness and type of ADR, and the medications involved.

A total of 922 suspected ADRs were reported in breastfed infants. Serious ADRs accounted for 133 cases (14%), with 15 reported fatalities, primarily associated with methadone (n = 11) and diamorphine (n = 3). COVID-19 vaccines were linked to half of the suspected ADR reports (n = 479, 52%), while serious ADRs were mainly associated with nervous system drugs (n = 73, 43%), particularly anticonvulsants and opioids. Most cases (n = 511, 55%) occurred in infants aged between 1 month and 1 year.

The reporting of 922 ADRs in breastfed infants over a decade, compared to the estimated millions of infants exposed to medications via mothers' milk annually in Europe, suggests a very low reporting rate of suspected ADRs. This finding emphasizes the significant challenges in postmarketing surveillance and suggests that underreporting remains a critical concern in pharmacovigilance.