How long does birth control not work after taking antibiotics?

Most antibiotics OK : Some antibiotics, like rifampin, definitely interact with birth control.Others may in some individuals and with some pills .It probably depends on how your body metabolizes the drugs, and it may also depend on the dose of hormones in the pills.Most small studies don't show differences in the level of hormones in the blood, but to be on the absolutely safe side, use condoms during antibiotic use.