1. Amoxicillin may reduce the efficacy of oral contraceptives; using additional non-hormonal contraception is advisable to prevent unintended pregnancy.

2. Amoxicillin can enhance the effect of anticoagulants like warfarin, increasing bleeding risk. Monitoring blood clotting time is recommended to adjust doses.

3. When taking amoxicillin with oral contraceptives, consider backup contraception due to potential decreased hormone absorption by antibiotics.

4. Amoxicillin interacts with warfarin by increasing its anticoagulant activity, possibly leading to excessive bleeding. Frequent INR checks are necessary.