Some antibiotics can decrease the effectiveness of your birth control pills, so you were doing the right thing by using a condom. No one knows how much of a decrease in effectiveness antibiotics cause. The effect may be dependent on such factors as type of antibiotic, length of treatment and previous pill use. Your birth control probably was not as good as usual, but it is still better than nothing. Worry? Not yet, but you can be concerned.
Continue taking your pills daily as usual. If your next period is more than 1 week late, do a pregnancy test.
BTW, for accidents like this,Plan B is a good option. Plan B helps prevent pregnancy by delaying ovulation (should you have a break thru ovulation due to the antibiotics use). It is available over the counter to women 17 and older. Women under 17 require a prescription. It costs about $46.
12. February 2012
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