Hello,
I have a question concerning the oral contraceptives and antibiotics- I take Qlaira- contraceptive- and yesterday I had sex which finished with ejaculation.Today I had to go to the dentist to have my tooth removed.The dentist gave me Keflex (cefalexin) to take for 6 days- 1000 mg a day.What Can I do about the yesterday;s sex as I HAVE TO take the antibiotic because of severe pain?Will the contraceptive pill stop working today and because of the yestredy's ejaculation the sperm will stay in me and now the antibiotic deminishes the contaceptive protection ?Thank you for the ansewer.

Depending on where you are in your cycle you may or may or not ovulate. The sperm will only last for maybe a day or two longer. That is neither here nor there considering your issue.

You need to take your antibiotics. Refrain from having unprotected sex, because you can really trust your pill for the rest of the cycle until you get your period. You should get it, but there is a chance, very small, that you could become pregnant. If you don't get your period two weeks after you should have then you take your home pregnancy test.

You should be okay from yesterday's sex. Having said that, no form of birth control is 100% effective, so there's always a chance of pregnancy when you have sex.

While on the antibiotics you should use an alternate form of birth control, or abstain from sex altogether.

Like Craven said, if you miss your next period wait 2 weeks then test using first morning urine.

Pregnancy can happen any time, even with 2 or more forms of birth control.