How long does it take the birth control pill to fully protect against pregnancy?

It Depends on when you started taking the pills.....

If you started taking your pills the very same day you started your period then you are protected immediately from the very first day. If you started taking the pills at any other time, like the Sunday after you started your period (which is the most common time to start taking pills because that is how most of the pill packs are set up), then you won't be fully protected from pregnancy for 7 DAYS. Make sure no more than 24 hours passes between active pills, or they are not as effective. Read the patient information insert that came with the pills, it will explain this in more detail, but if you still have questions, please call your doctor. Source(s): Successful user of birth control pills for the past 15 years. Switched to Seasonale when it became available in the U.S.( Only 4 periods a year ladies!!!! It has changed my life!!!)

It's a good answer, but birth control pills are not "fully protective" against pregnanacy. There's a lesser chance, pills are only 98-99% effective. There are still that 1% that get pregnant no matter what. The only true protection is abstinence.

to add since i can only use 300 charecters, my 2 youngest are a direct result of me and their dad using birth control. so if you absolutely have to, make sure you "double up". have him use a condom too.

24 hours