Plan B, or emergency contraception, is used to prevent any unwanted pregnancy when the first form of birth control fails. According to the Feminist Women's Health Center, the first dose of Plan B should be taken within 120 hours of intercourse. However, the sooner Plan B is taken, the more effective it is. Plan B works by changing the uterine lining, thus preventing implantation. Plan B will not terminate an already existing pregnancy. Plan B does have some side effects, most of which go away in one to two days. Side effects that last longer are a cause for concern.
Common Side Effects
According to the Feminist Women's Health Center, common side effects from Plan B use are headaches, fatigue, dizziness, lower abdominal pain and breast tenderness. None of the side effects are serious and should go away within a day or two. In addition, some women may feel queasy and throw up after taking Plan B. If that occurs within 30 minutes of taking the first dose of Plan B, the woman should call her doctor or clinic, because this can affect the absorption and effectiveness of the medication. To prevent any vomiting, a woman should take an anti-nausea medication before using Plan B. Also, the hormones in Plan B can cause unexpected bleeding; it should be a little spotting before the woman's next period and will also go away after a few days.
Period
Plan B can also cause a disruption in a woman's normal period. According to the Feminist Women's Health Center, the woman's period can come a week earlier or a week later than normal. However, if the woman doesn't have her period within two weeks of taking Plan B, she should take a pregnancy examination.
Danger Signs
Plan B is safe for most women, but it can cause some dangerous side effects in some. According to the Feminist Women's Health Center, danger signs from Plan B use include severe abdominal pain, chest pain, shortness of breath, severe headaches, blurred vision and severe pain or numbness in the woman's leg or arm. These side effects may not go away after a day or two and can indicate a serious problem. If a woman experiences any of these dangerous side effects, she should seek medical attention immediately.
