Question: how long does it take for birth control to work if you miss a day?
Answer: Take your missed pill as soon as possible (which means you may need to take two pills in one day). Continue with the rest of the pack as usual. No. But if it's been longer than 48 hours since you last took a pill you need to use a 7-day, non-hormonal back-up method (such as a condom and spermicide).