Emergency contraception can help prevent pregnancy when your birth control fails (whether the condom breaks or you forget a pill or two), but whether you need to see a doctor first depends on the type you choose. While emergency contraception is often referred to as the morning-after pill, there are actually two different medications you can choose from — one that requires a prescription and one that does not — and the most effective form of birth control when you’re in a pinch isn’t a pill at all, but a copper IUD.
Here, I’ll explain exactly how each method works and why you might choose one over the other. Just remember, no form of emergency contraception can help prevent STIs, so if you’ve had unprotected sex and you’re concerned about your risk, make an appointment to get screened.
1. Progestin-Only Emergency Contraceptive Pill
Known commercially as Plan B, Next Choice One Dose, and other brand names, the progestin-only pill comes in a single 1.5mg dose or two doses of 0.75mg. The active ingredient, levonorgestrel, works by delaying ovulation and thickening the cervical mucus to act as a barrier to sperm.
Why you might try it: The progestin-only morning-after pill can be purchased without a prescription or an appointment with your doctor. There are also very few restrictions for use: you can take the pill along with other birth control, for example, and even use it more than once in the same month.
What you should know: Progestin-only pills are most effective when taken within three days of unprotected sex, and they may not work as well for people with a body mass index (BMI) over 26. While it’s safe to start a combined estrogen-progestin pill immediately after taking this form of emergency contraception, you shouldn’t rely on it to prevent pregnancy for at least seven days.
2. Ulipristal Acetate Emergency Contraceptive Pill
UPA is most commonly sold under the brand name Ella, and it works a bit differently from the progestin-only pill, by delaying ovulation even after the brain has signaled the ovary to release an egg.
Why you might try it: Because of the progestin-blocking mechanism that helps prevent ovulation even after that signal is sent, UPA is more effective five days after unprotected sex. It’s also more effective closer to ovulation and in people with a higher BMI.
What you should know: Unlike the progestin-only pill, you do need a prescription to get UPA and may even need to visit your healthcare provider. Not all pharmacies carry emergency contraception, so the sooner you reach out to your doctor, the better. You’ll also need to wait five days before starting or continuing any type of hormonal contraception, as taking birth control can prevent UPA from working as effectively. (Nonhormonal methods are fine!) Additionally, you can only take UPA once per cycle, and people with severe asthma or liver disease should avoid it.
3. Copper IUD
The copper IUD is the only intrauterine device that can serve as emergency contraception, as it begins working to prevent pregnancy immediately. It essentially works as a spermicide, killing sperm before it can fertilize an egg.
Why you might try it: The copper IUD is the most effective form of emergency contraception. It works best if it’s inserted within five days of unprotected sex, but your doctor may be able to place it later than that, as long as they can estimate that it’s within five days of ovulation.
What you should know: You’ll obviously need to see a doctor to get an IUD. Insertion can be crampy and painful, and the copper IUD may cause irregular bleeding.
4. Combination Pills
Certain types of standard birth control pills — which contain a combination of estrogen and progestin — can be used as emergency contraception, by mimicking the effects of the progestin-only pill. The key is finding the appropriate dose.
Why you might try it: If the birth control you’re on is among the medications included in this chart from Princeton, taking the listed dosage can help prevent pregnancy, while allowing you to conveniently avoid a trip to the doctor’s office or pharmacy.
What you should know: Taking high doses of combined oral contraceptives — and more specifically, estrogen — can increase your risk for disorders like blood clots in the legs and lungs, and cause side effects like nausea, vomiting, and headaches. It’s important to consult your doctor before taking a higher dose to ensure it’s safe, given your medical history.