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antibiotics reducing the effectiveness of the pill.

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Hello. I was on antibiotics for 2 weeks (Clindamycin) for a mouth infection. Although I'm on the birth control pill, my partner and I had sex last Wednesday (10/1) because I was totally oblivious to antibiotics possibly reducing the effectiveness of the pill.

I finished the last pill in my pack on Monday (10/6) and am now scared because I have not yet started my period (2 days late) and have only had a little spotting.

Is it likely that I'm pregnant if the sex was so late into my cycle? Could it be the antibiotics just made my period this month irregular? Because of the close proximity between the sex and my late period, how long should I wait to take a test? Thank you!

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replied October 10th, 2014
Am I Pregnant Answer A49542
Welcome to the ehealthforum. I am glad to help you out.

It is true that antibiotics can effect the efficacy of the birth control pills. But pregnancy occurs only during the time of ovulation. Ovulation is the release of a single, mature egg from a follicle that developed in the ovary. It usually occurs regularly, around day 14 of a 28-day menstrual cycle.

Since you did not have any unprotected intercourse close to ovulation and have been taking the pills regularly, chances of pregnancy are less.

If you are apprehensive regarding the status of your pregnancy you can get it checked. Most home pregnancy tests that check urine beta-HCG are sensitive to 20-25 mIU/ml of HCG. The test can be positive anywhere from about 2-3 days prior to a missed menses to 4-5 days after, but usually it should be done 7-10 days past your missed period.

It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care.

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