I have been on oral contraceptives for a year now, and I just started my monthly pack 1 day ago (after being on my sugar pills for 7 days). I had unprotected sex last night, (He didn't go in me), and got prescribed Macrobid to take. Is it safe for me to take the Macrobid or will I be able to get pregnant from the sex last night?
It may interfere with your birth control. Although there is no proof that it it does, it is thought to have the ability to do so. (Nitrofurantoin - Brand names: Furadantin, Macrobid, Macrodantin, Nitro Macro)
Contrary to common wisdom, only certain ones do for sure, and some are thought to be able to do so.
Your risk is likely very very low (you have been on BCPs for a while, it is only thought to be able to interfere, he did not ejaculate inside you, it happened a while ago), but you need to speak to your doctor about it if you are worried.