There are three main types of emergency contraception: Plan B, the Copper IUD, and Ella.

Plan B (the morning-after pill) contains levonorgestrel. It works best within 72 hours of unprotected sex, but you can still take it up to five days after. The longer you wait, the less it works.

The Copper IUD is a small device a healthcare provider inserts into the uterus. It's normally a long-term birth control option, but it doubles as emergency contraception. Inserted within five days of unprotected sex, it's extremely effective. The copper ions are toxic to sperm, so fertilization doesn't happen in the first place.

Ella is a prescription-only pill in Canada, containing ulipristal acetate. It blocks the hormones needed for conception and works for up to five days after unprotected sex. It's generally more effective than Plan B, especially for women with a higher BMI.

What's the most effective type of emergency contraception?

The Copper IUD wins on effectiveness, cutting pregnancy risk by more than 99%. Among pills, Ella (ulipristal acetate) edges out Plan B (levonorgestrel), especially later in the five-day window. The catch with the Copper IUD is access: you need a sexual health clinic to insert it, since Ontario pharmacists don't offer this service. The reason it works so well is that the copper creates a hostile environment for sperm, preventing fertilization in the first place. Bonus: you walk out with long-term birth control.

Morning-After Pills: Ella vs. Plan B

Ella is often preferred over Plan B because it's more effective. Clinical studies put Ella's failure rate at 0.9% to 2.1%, slightly lower than levonorgestrel-based options.

Ella also holds up better as time passes after unprotected sex. The research shows it outperforms levonorgestrel in the 24 to 72 hour window, which is exactly when most people end up taking emergency contraception.

Can emergency contraception fail?

Yes. It's a strong tool for preventing unintended pregnancy, but nothing in this category is 100%.

How soon should you take it?

The sooner the better. Emergency contraceptive pills work best the earlier you take them. Plan B (levonorgestrel) should ideally be taken within 72 hours (3 days). Ella (ulipristal acetate) works up to 120 hours (5 days). The Copper IUD can be inserted up to 5 days after unprotected sex and stays highly effective the whole time.

Timing matters most for the pills. Plan B loses effectiveness fairly quickly. Ella holds up a bit longer but is still best in the early hours. The Copper IUD doesn't depend on this timing the same way: its mechanism keeps it reliable across the full 5-day window.

Can you use emergency contraception as regular birth control?

No. EC isn't meant for regular use. It's less effective than standard contraceptives, and it doesn't protect against STIs. The whole point is to cover one-off situations: unprotected sex, a broken condom, missed pills.

Regular birth control (the pill, condoms, IUDs) prevents pregnancy more reliably. Condoms have the added benefit of STI protection. Treat EC as a backup, not a routine method.

How often can you take EC pills?

Plan B: there's no hard limit on how often you can take it, but it's not designed for repeat use. Taking it frequently can mess with your cycle, cause unexpected bleeding, and shift your period. It's also less effective than regular birth control and doesn't protect against STIs.

Ella: same idea. No set limit, but frequent use can throw off your cycle and may reduce its effectiveness over time.

Can you take EC pills while on birth control?

Yes, in certain situations. If your regular method fails (a missed pill, a broken condom), EC adds another layer of protection against pregnancy.

Plan B contains levonorgestrel, the same hormone in many birth control pills. Taking it while on the pill is safe. You may get nausea or a slightly off next period, but it won't affect how well your regular birth control works going forward.

Ella is different. Ulipristal acetate can interact with hormonal birth control, so talk to your provider before using it if you're on the pill. After taking Ella, you'll typically need to use a backup method like condoms for a short period, per your provider's instructions.

Side effects of emergency contraception

EC is safe for almost everyone. Your specific medical history and medications can make one option a better fit than another. Plan B and Ella can have different interactions and contraindications, while the Copper IUD is a non-hormonal alternative for people who can't use hormonal EC.

Side effects are usually mild and short-lived. Expect things like nausea, fatigue, headaches, breast tenderness, and a shift in the timing or flow of your next period. These pass quickly once the hormones clear your system.

Watch out for severe abdominal pain after taking EC. That can be a sign of something serious like an ectopic pregnancy and needs medical attention right away. Anything intense or lasting longer than expected is worth a call to your provider.

Does body weight affect how well EC works?

Yes, for the pills. Studies show EC pills lose effectiveness in people with higher body weight, particularly with a BMI over 35. If that applies to you, it's worth factoring into your choice of method.

The Copper IUD isn't affected by body weight. It works the same way regardless of your size because it relies on the copper creating a hostile environment for sperm, not on hormone levels in your bloodstream.

Can emergency contraception cause an abortion?

No. EC prevents or delays ovulation, or prevents fertilization. It works before pregnancy starts. If a fertilized egg has already implanted, EC won't do anything to that pregnancy.

The confusion comes from how people picture these drugs working. Plan B and Ella mainly delay ovulation. The Copper IUD creates a spermicidal environment that stops fertilization. None of these affect an embryo that's already implanted.

Does EC work during ovulation?

Less so. EC pills are most effective before ovulation, because their job is to prevent or delay the egg's release. If you've already ovulated, the pills don't have much to work with.

Plan B and Ella are designed to push ovulation off. If your body's already mid-cycle or past it, that effect is reduced. The Copper IUD is the exception: it works regardless of where you are in your cycle because it acts on the sperm, not the egg.

Bottom line: time matters for the pills. Take them as soon as you can after unprotected sex.

Does EC protect against STIs?

No. None of these methods do anything against sexually transmitted infections. They're designed to prevent pregnancy and nothing else.

See our FAQ for additional details on emergency contraception.

Bottom Line

EC is a key safety net, but it's not a substitute for regular birth control and it won't protect you from STIs. Which method is right for you depends on timing, your medical history, and what's available. Talk to a healthcare provider to figure out the best option for your situation.

Disclaimer: This blog post is intended for educational purposes only and should not be taken as medical advice. Always consult your healthcare provider for personal health concerns.