LHello, I have to take Amoxicillin 875 mg for 10 days, due to Sinusitis. I am on the implanon birth control. What are the chances of me getting pregnant while taking this? I ve heard that antibiotics decrease the effectiveness of birth control and I m scared.. Also, how likely am I to get pregnant if I take St. Johns Wort while on implanon? I have been on many different anti-depressants in the past year, my doctor is trying to see what works for me and nothing has been working. I d like to try this OTC medication, because Ive heard very good things about it. Please include percentages on how often both of these cause pregnancies, if possible. Thank you!