Plan B

Generic name: Levonorgestrel

Why is Plan B prescribed?

Plan B is intended as "morning after" birth control to prevent pregnancy after known or suspected contraceptive failure (for instance, a broken condom) or unprotected sex. Plan B treatment must begin within 72 hours after having sex.

Plan B contains only one hormone, a progestin. It may prevent a pregnancy but will not end one that has already begun. It is believed to work mainly by inhibiting ovulation (release of an egg) and fertilization. It may block implantation of the egg in the lining of the uterus. It is not effective once the process of implantation has begun.

Most important fact about Plan B

Plan B is meant for emergency use only and not as a regular method of birth control. It is not as reliable as regular birth control. Using Plan B correctly after a single act of unprotected sex reduces the average chance of pregnancy to about 1 percent.

How should you take Plan B?

Plan B comes in a package with two tablets. Take the first tablet as soon as possible after having sex, within 72 hours at the latest. Take the second tablet 12 hours after the first one. You can take Plan B at any time during your menstrual cycle.

--If you miss a dose...

Call your doctor immediately. Your chances of pregnancy increase when you do not take the pills as prescribed.

--Storage instructions...

Store at room temperature.

What side effects may occur?

Side effects cannot be anticipated. If any develop or change in intensity, tell your doctor as soon as possible. Only your doctor can determine if it is safe to continue using Plan B.

• More common side effects may include:
  Abdominal pain, breast tenderness, diarrhea, dizziness, fatigue, headache, menstrual changes, nausea, vomiting

Why should Plan B not be prescribed?

Do not take Plan B if you have had an allergic reaction to progestin, the type of hormone found in the drug. You should also avoid this medication if you have any unexplained vaginal bleeding.

Special warnings about Plan B

Remember that Plan B should not be used as a regular form of birth control, and it will not work if you are already pregnant.

Plan B may affect your next menstrual cycle by delaying it or making it much heavier or lighter than normal. It could also cause spotting between cycles. If your next period is delayed by more than a week, you should consider the possibility that you may be pregnant.