Question : How long does it take for oral contraceptives to become effective after being on antibiotics?
I use oral contraceptives alone for birth control, and was prescribed a seven day course of Macrobid. I did have break through bleeding on the second day… When do the oral contraceptives become effective again in preventing pregnancy?
contraceptives

Best answer:

Answer by Steph
i believe like 3 or 4 days.. for the meds to get out of your system.. if i were you just to play it safe i would wait 7 days or use condoms too