Started Birth Control, But Then Had Unprotected Sex

How effective is the birth control pill?

As for the general effectiveness of birth control pills, Planned Parenthood states that:

When used perfectly, the pill is 99% effective. But when it comes to real life, the pill is about 91% effective because it can be hard to be perfect. So in reality, 9 out of 100 pill users get pregnant each year.

The better you are about taking your pill every day and starting your pill packs on time, the better it will work. You can use our birth control app to remind you to take your pills everyday. But there’s a very small chance that you could still get pregnant, even if you always take your pills correctly.

How long do I need to take birth control pills for them to be effective without a back-up method of birth control?

In terms of your question about how long birth control pills take to be effective, it depends on what kind of birth control pill you are taking. According to Planned Parenthood:

It depends on when you start taking them. You can take your first birth control pill any day of the month, but you may need a backup birth control method (like condoms) for the first 7 days.

Combination Pills (COCs)

If you start combination pills within 5 days after your period starts, you’ll be protected from pregnancy right away. For example, if you get your period Monday morning, you can start the pill anytime until Saturday morning and be protected from pregnancy right away.

If you start combination pills any other time, you’ll be protected from pregnancy after 7 days of taking the pill. Use another method of birth control — like a condom or female condom — if you have vaginal sex during the first week you’re on the pill.

Progestin-Only Pills (Mini Pills)

You can start progestin-only pills at any time. You’ll be protected from pregnancy after 48 hours (2 days). So use another method of birth control (like condoms) if you have vaginal sex during the first 48 hours.

Your nurse or doctor can help you figure out the best time to start your birth control pills, and when they’ll start working for you.

Given that you took the pill for 13 days before having unprotected sex, the chances would be very low that you would be pregnant. However, it might be best to check in with the doctor who prescribed you your pills just to be sure.

For more information about birth control pills, click here. And please be aware that the pill does not protect against STDs.

If you don't have a doctor and live in northern New Jersey, you can call the Adolescent/Young Adult Center for Health at 973-971-5199 for an appointment with an adolescent medicine specialist or contact your local teen health center or Planned Parenthood. A Planned Parenthood health center is a good option if you have concerns about cost or confidentiality issues. You can also contact your insurance company for a list of in-network providers.