How long after starting the pill for the first time does it take for it to become 99% effective in your body?
It depends on whether you’re taking combination pills or progestin-only pills, and where you're at in your menstrual cycle. You can start taking both types of pills at any time, but you may have to use a backup method of birth control (like condoms) for up to the first 7 days.
For combination pills (COCs): If you start within 5 days after your period starts, you’re protected from pregnancy right away. You won’t need to use a backup method of birth control. That means that if your period comes on a Wednesday morning, you can start the pill up to the following Monday morning to be protected right away. If you start at any other time during your menstrual cycle, you’ll be protected from pregnancy after 7 days of using the pill. Use another method of birth control — like a condom — if you have penis-in-vagina sex during the first 7 days on the pill.
For progestin-only pills (POPs or mini pills): Pregnancy protection begins after 2 days on the pill, no matter when you start taking them. Use another method of birth control — like a condom — if you have vaginal sex during those first 48 hours (2 days) on the pill
You must take progestin-only pills at the same time every day. If you take it more than 3 hours past your usual time, use a backup method of birth control for the next 48 hours (2 days).
A newer type of progestin-only pill called Slynd works a little differently. If you start taking Slynd within the first 5 days of your period, you’ll be protected from pregnancy right away. If you start taking Slynd at any other time in your cycle, use another method of birth control (like condoms) if you have penis-in-vagina sex during the first 7 days. And you don’t need to take Slynd within the same 3 hours every day, like you do with other progestin-only pills.
If you have more questions about your birth control pills, call your nurse or doctor, or your local Planned Parenthood health center. You can also chat online or text "PPNOW" to 774636 (PPINFO) to speak with one of our live health educators — it’s totally free and totally confidential.