Is there any birth control pill that only takes a couple of days or weeks to become effective?
Yes — all birth control pills start protecting you from pregnancy within seven days, if not immediately.
Combination birth control pills will protect you from pregnancy immediately if you start taking them within five days of the start of your period (so if your period starts on a Wednesday morning, you can start the pill up to Monday morning and be protected right away). But don’t worry if you’re not menstruating and you want to start the pill—you can start at any point during your cycle. If you’re not starting within the first five days of your period, you’ll be protected after seven days of taking it, so make sure you use a back-up method, like a condom, for those first seven days.
The progestin-only pill is a little different. You can still start at any time during your menstrual cycle, but with this pill, protection starts after two days, or 48 hours. So you’ll need a back-up method if you have sex during these first two days.
A lot of people think you can only start birth control pills at a specific time during your cycle, or that they take 30 days to become effective. This isn’t true. You can start at any time, and as long as you’re taking the pills correctly, it takes only seven days at the most for you to be protected against pregnancy.
Just remember that the pill does not protect you against STDs. Using a condom along with the pill will give you great protection against pregnancy and really reduce your risk of getting an infection.