context: Your doctor or pharmacist can help you get answers about emergency contraception. You may want to ask them: There are lots of good options. But the best one for you depends on different things. Your age, for instance -- some nonprescription products have age limits. Your insurance may pay only for a prescription. When you had sex can matter, too. Some products work for about 3 days after, some for 5. Your doctor or pharmacist can steer you in the right direction. The copper- T intrauterine device ( IUD) can work as emergency contraception. The IUD goes inside your body. If you want an IUD, a nurse or doctor needs to put it in within 5 days of when you had sex. The IUD works as both emergency contraception and as ongoing birth control. It prevents pregnancy as long as it is in place. The copper IUD is the most effective form of emergency contraception. . Ask your doctor if an IUD might be a good choice for you, especially if you already wanted long-term birth control. There are 3 types of emergency contraception in pill form that are sold both with and without a prescription. You need to be 17 to buy them if a prescription is needed. Depending on the brand and dose, you might get 1 pill or 2. 1. Pills containing a hormone called levonorgestrel: My Way (over-the-counter) Plan B One- Step (over-the-counter) Preventeza (over-the-counter) Take Action (over-the-counter) 2. Birth control pills can also be used as emergency contraception, but you have to take more than one pill at a time to keep from getting pregnant. This approach works, but it is less effective and more likely to cause nausea than levonorgestrel. Birth control pills require a prescription. Talk to your doctor or nurse to make sure you are taking the correct pills and dose. 3. A third kind of emergency contraception pill is called ulipristal (ella, ella One). You need a prescription to get it. Some meds and supplements -- such as the epilepsy drug Dilantin, antibiotics such as rifampicin or griseofulvin, and St. John's wort -- can stop emergency contraception pills from working normally. To be safe, tell your doctor or pharmacist about other drugs and supplements you take. Emergency birth-control pills and the IUD are safe for almost all women. But if you have medical problems and you're concerned that taking emergency contraception could be risky, talk to a doctor or pharmacist. The pills may not work as well for women who are overweight or obese. It may be awkward to discuss, but ask a pharmacist or doctor. If you're overweight, Ella may work better than Plan B One- Step and generic levonorgestrel. In general, the IUD seems to work better than pills for heavier women. You should use a regular form of birth control right away. Emergency contraception lasts only for about 24 hours and may just delay ovulation, not stop it. Make sure you're protected. Some types of emergency contraception may not be safe if you're already pregnant. Most pills won't harm your pregnancy. But you should not take Ella if you think you might be pregnant. It's not safe. Prices can vary. They depend on the type of pill, the store, and other things. Find out what your choices are and compare the costs.