Medical Questions > Womens Health > Birth Control Forum

can antibiotic affect the pill if taken 30 hrs after sex?

I have post this question before but never really gt any reply . So am
Posting it again .

My girlfriend has been on the pills for 1 and a half years now, 2 weeks ago, we had unprotected sex and I ejaculate inside her. About 30 hours later that, she took antibiotic that is given by doctor and was told that the antibiotic will make the pills ineffective.

I have been reading article online and none of it describe my situation. Because all of the situation discuss mention that all antibiotic was taken before sex .

My gf situation:
Take 1.5 years of birth control
Have unprotected sex
30 hours later took some antibiotic

Is there a chance of her getting pregnant?

Oh . And also because the anti biotic suppose to be for 5 days . She miss some here and there and took her a week to finish it .

I left out some info ,

We had unprotected sex on Thursday afternoon, she took the antibiotic on Friday night , than the following Wednesday, she had her period.

Does that made any difference?

Thanks !
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replied June 1st, 2011
Welcome to ehealthforum,
If she has had her normal periods after intercourse and use of antibiotics, the chances of pregnancy can be ruled out. Antibiotics are known to affect the efficacy of birth control pills and if you have intercourse while she is on the antibiotics, chances of pregnancy can be present. She should be regular with the birth control pills use (without missing pills in between) to continue to have protection. Wait and watch for her next periods. Look out for development of any other new symptoms suggestive of early pregnancy if pregnancy is suspected.
Take care.

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