Minor
Ethinylestradiol × Norfloxacin
Estrogens. Natural and semisynthetic estrogens, plain×Second-generation fluoroquinolone
Mechanism
Norfloxacin does not induce CYP3A4 and does not affect ethinylestradiol metabolism. The historical theory of reduced COC efficacy is rejected by meta-analyses.
Symptoms
The combination usually causes no specific symptoms. Each drug's individual side effects remain.
Management
Additional contraception during short norfloxacin courses (3–7 days) is not needed.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.