Minor
Amoxicillin × Ethinylestradiol
Penicillins with extended spectrum×Estrogens. Natural and semisynthetic estrogens, plain
Mechanism
Historical theory of reduced combined oral contraceptive efficacy via gut flora suppression. Cochrane meta-analysis (2017) did not confirm clinically significant reductions in ethinylestradiol levels with broad-spectrum antibiotics other than CYP3A4 inducers (rifampicin, rifabutin).
Symptoms
The combination usually causes no specific symptoms. Each drug's individual side effects remain.
Management
Additional contraception during short amoxicillin courses is not needed (updated WHO Medical Eligibility Criteria 2015). The old "use a barrier method for the whole cycle" practice is outdated and applies only to rifampicin, rifabutin, CYP3A4-inducing anticonvulsants (carbamazepine, phenytoin), and most HIV antivirals.
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.
Sources
- KDIGO: KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of CKD (2024)– Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int 2024;105(4S):S117-S314.