Retamal-Valdes B, Tavares A P L, Monique S et al. Adverse events of metronidazole and amoxicillin: retrospective analysis of a large data set of five randomised clinical trials. J Clin Periodontol 2022; DOI: doi: 10.1111/jcpe.13704. Online ahead of print.

Diabetics, patients under 49 years old and women tended to report more side effects.

This study aimed to evaluate the frequency of side effects associated with intake of metronidazole (MTZ)+ amoxicillin (AMX) in periodontal treatment. Data from five randomised clinical trials testing MTZ + AMX adjunctive to mechanical therapy were evaluated. Information from 656 subjects was assessed. The frequency of side effects in the antibiotic- and placebo-treated groups ranged from 1.0%-17.7% and 0.9%-13.7%, respectively. The events more frequently observed in the antibiotic than in the placebo group were diarrhoea and a metallic taste. Diabetes significantly raised the odds of a patient reporting discomfort, diarrhoea, weakness and excessive sleepiness. In systemically healthy volunteers, using antibiotics three months post-mechanical treatment (healing phase), being a woman and aged<49 years significantly increased the chances of reporting adverse events.