Amoxicillin is widely prescribed, either as a monotherapy or in combination with clavulanic acid, with its therapeutic indications including a broad range of infections. Its combination with clavulanic acid maintains its known activity against strains producing β-lactamase. There are limited studies on adverse reactions and antibiotic resistance, with researchers relying primarily on databanks that report spontaneous events caused by amoxicillin or the combination of amoxicillin/clavulanic acid. Antimicrobial resistance is an overlooked adverse event, and pharmacovigilance databases could serve as a tool in tracking resistance. On this basis, a study to define the safety profile of amoxicillin and amoxicillin/clavulanic acid and to increase the knowledge necessary to support the battle against antimicrobial resistance was undertaken through the analysis of pharmacovigilance databases. Suspected adverse reactions to amoxicillin and to the combination of amoxicillin/clavulanic acid in the data system EudraVigilance (2020-2024) were analyzed. The most frequent alerts concerned "Skin and subcutaneous disorders" for both drugs. Disproportionate analysis of cases concerning "Hepatobiliary disorders" or "Drug inefficiency" indicates a significant increase in these alerts with the amoxicillin/clavulanic acid combination compared to amoxicillin. The amoxicillin/clavulanic acid combination has previously been associated with a higher risk of hepatotoxicity and antibiotic resistance to amoxicillin/clavulanic acid; however, this is the first time that a post-marketing surveillance study has shown that antimicrobial resistance is more likely to occur with the combination in comparison to amoxicillin alone.
Keywords: adverse reactions; amoxicillin; amoxicillin/clavulanic acid; antibiotic resistance; antimicrobial resistance; hepatotoxicity; liver toxicity; pharmacovigilance.