How does the emergency contraceptive pill work?
Levonorgestrel, the medication found in Plan B One Step, Take Action, Next Choice One Dose, My Wayand other levonorgestrel emergency contraceptive pills prevent pregnancy by stopping or delaying the release of the egg from the ovary. Emergency contraceptive pills may also alter the lining of the uterus to prevent egg implantation or reduce the ability of the sperm to bind to an egg. The levonorgestrel 1.5 mg emergency contraceptive pill should be taken within 72 hours after unprotected sex. It can lower your chance of getting pregnant by 75% to 89%, but it works best the sooner you take it.
Some research suggests that levonorgestrel emergency contraceptive pills may not be fully effective in women who are overweight or obese, but this is controversial topic. In 2016 the U.S. Food and Drug Administration (FDA) determined that a change in the labeling for emergency contraceptive products is not warranted in women who weigh more than 165 lbs (75 kg) or have a body mass index (BMI) of more than 25 kg/m2. The FDA stated the data are conflicting and too limited to reach a definitive conclusion. The FDA continues to believe all women, regardless of how much they weigh, can use the levonorgestrel emergency contraceptive to prevent unintended pregnancy following unprotected sexual intercourse or contraceptive failure.
Ulipristal, the progestin found in the emergency contraceptive pill ella, works to prevent pregnancy by blocking the natural hormone progesterone from occupying its receptor site in the body. It is more effective than the levonorgestrel emergency contraceptive pill, and can be used up to 5 days after unprotected sex; however, it requires a prescription. ella or the copper IUD may be a better option for emergency contraception in women if it longer than 72 hours since unprotected sex. After use of ella, a reliable barrier method of contraception should be used with sexual intercourse that occurs in that same menstrual cycle.
If you take combined birth control pills (often just called "the "pill") that contain both estrogen and progestin, and have no other options, higher doses can be used as an emergency contraceptive. They work by delaying ovulation, and the number of pills you would use for each brand of pill will differ between brands or generics. A doctor, clinic nurse, or pharmacist can tell you how many pills you should take based on the type and brand of oral birth control that you use.
If you should miss your period by more than one week, you should have a pregnancy test