When You Need A Plan B, Here’s How Emergency Contraception Works

Published: March 16, 2021Updated: March 22, 2021

Even if you’re the one in your friend group who always packs extra snacks and a pack of hand wipes, there are times in life where things don’t go according to plan. Maybe you forgot to take your birth control for a few days, or the condom broke, and you want to cover all your bases to prevent a pregnancy. 

In those situations, taking emergency contraception after having unprotected sex will decrease your changes of getting pregnant. Here’s how emergency contraception works and how to take it effectively.

What is emergency contraception?

Emergency contraception is any type of contraception that can be taken after sexual intercourse to prevent pregnancy. While it’s considered best practice to take emergency contraception as soon as possible after intercourse, some methods can be effective for up to five days afterwards.

The most common type of emergency contraception is a pill, and in the United States, three options are available: ulipristal acetate-based, progestin/levonorgestrel-based, and progestin and estrogen-based. Each one has different rates of efficacy and different side effects, and only ulipristal acetate-based (which is sold under the brand name ella) requires a prescription.

Another method of emergency contraception is getting an IUD inserted within five days of unprotected sex. Getting an IUD put in has the bonus of protecting you from pregnancy for up to ten years after insertion (or whenever you decide to take it out). But, since getting an IUD is a little more labor-intensive than taking a pill, it’s usually seen as more of a preventive measure than an emergency contraceptive method. 

How does emergency contraception work?

Emergency contraception works by preventing or delaying ovulation—similar to your regular birth control. You’ll take a pill that’s imbued with a large dose of hormone (like levonorgestrel, which is in Plan B One-Step, or ulipristal acetate, which is in ella) that works to suppress ovulation, block fertilization from occurring, or prevent a fertilized egg from implanting in the uterus.

And listen closely for a sec: emergency contraception is not the same as an abortion pill. While an abortion pill terminates an existing pregnancy, an emergency contraception pill prevents a pregnancy for occurring. Remember, it can take several days for an egg to get fertilized and then implant in the uterine wall. Pills like Plan B or ella interrupt that process in the days following unprotected sex, but they don’t terminate any impregnation that’s already occurred.

So, if abortion is something you have complicated feelings on, rest easier knowing that emergency contraception is totally, completely different from an abortion pill.

How do you take emergency contraception effectively?

Four letters: ASAP. The sooner you take emergency contraception pills, the more effective they are—and the lower your chance of getting pregnant is. Taking the dose within 24 hours is ideal, if possible. However, this does vary slightly among brands: Plan B One-Step can reduce pregnancy rate by 88%, but its effectiveness drops after 24 hours. Meanwhile, ella maintains the same level of effectiveness up to the fifth day after unprotected sex. 

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