Will amoxicillin reduce effectiveness of oral contraceptive?

Question: I have a sore throat, swollen and purulent. The doctor prescribed me amoxicillin. But now I am taking oral contraceptives. 

Do I suspect that amoxicillin will reduce the effectiveness of oral contraceptive or not?

Answer: There is the data about drug interaction between contraceptive and amoxicillin that may reduce effectiveness of oral contraceptive.

In the past, a few clinical cases had been reported that had failure to prevent pregnancy when they ate amoxicillin with oral contraceptive. However, there is no study quality and reliable enough to be supported.

In such cases, if the patient becomes infectious diseases in the upper respiratory tract, which is necessary to take antibiotics. It is recommended that patient should be taking received amoxicillin.

If a patient is worry about the pregnancy, it is recommended to use oral contraceptive in combination with other method of contraception, such as the condoms, during taking amoxicillin and further seven days after finishing amoxicillin.

Reference:

1. Zhanel GG, Siemens S, Slayter K, Mandell L. Antibiotic and oral contraceptive drug interactions: Is there a need for concern? Can J Infect Dis 1999; 10 (6): 429-33.