July 27, 2016
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Plan B

"Today, the U.S. Food and Drug Administration announced it has approved the use of Plan B One-Step (levonorgestrel) as a nonprescription product for all women of child-bearing potential. This action complies with the April 5, 2013 order of the Uni"...


Plan B


Plan B®
(levonorgestrel) Tablets 0.75 mg
Emergency Contraceptive

What is Plan B® (levonorgestrel) ?

Plan B® (levonorgestrel) is emergency contraception. Emergency contraception is a backup method of preventing pregnancy and is not for routine use. Drugs used for emergency contraception are called emergency contraceptive pills, postcoital pills, or morning after pills. Plan B® (levonorgestrel) can reduce your chance of pregnancy after unprotected sex (if your regular birth control method fails or if you have had sex without birth control). For example, if you were using a condom and it broke, or if you forgot to take 2 or more of your birth control pills this month, or if you did not use any birth control method, Plan B® (levonorgestrel) may work for you.

How does Plan B® (levonorgestrel) work?

Plan B® (levonorgestrel) contains a dose of the hormone levonorgestrel that is higher than in a single birth control pill. Levonorgestrel has been used in birth control pills for over 35 years. Plan B® (levonorgestrel) works like a birth control pill to prevent pregnancy mainly by stopping the release of an egg from the ovary. It is possible that Plan B® (levonorgestrel) may also work by preventing fertilization of an egg (the uniting of sperm with the egg) or by preventing attachment (implantation) to the uterus (womb), which usually occurs beginning 7 days after release of an egg from the ovary. Plan B® (levonorgestrel) will not do anything to a fertilized egg already attached to the uterus. The pregnancy will continue.

When is it appropriate to use Plan B® (levonorgestrel) ?

You can use Plan B® (levonorgestrel) after you have had unprotected sex 1 or more times in the last 3 days (72 hours), and you don't want to become pregnant.

Plan B® (levonorgestrel) can be used as a backup method to birth control if, for example,

  • Your regular birth control failed (your partner's condom broke or slipped)
  • You made a mistake with your regular method (you missed 2 or more birth control pills this month)
  • You did not use any birth control method

When is it not appropriate to use Plan B® (levonorgestrel) ?

  • Plan B® (levonorgestrel) should not be used as a regular birth control method. It does not work as well as most other forms of birth control when they are used consistently and correctly. Plan B® (levonorgestrel) is a backup or emergency method of contraception
  • Plan B® (levonorgestrel) should not be used if you are already pregnant because it will not work
  • Plan B® should not be used if you are allergic to levonorgestrel
  • Plan B® (levonorgestrel) does not protect against HIV (the virus that causes AIDS) or other sexually transmitted diseases (STDs). The best ways to protect yourself against getting HIV or other STDs are to use a latex condom correctly with every sexual act or not to have sex at all

How can I get the best results from Plan B® (levonorgestrel) ?

You have only a few days to prevent pregnancy after unprotected sex. Plan B® (levonorgestrel) works better the sooner you take it. Take the first Plan B® (levonorgestrel) tablet as soon as possible but not later than 3 days (72 hours) after unprotected sex. Take the second tablet 12 hours later.

How effective is Plan B® (levonorgestrel) ?

Plan B® (levonorgestrel) works best the sooner you use it. If it is taken within 72 hours (3 days) after sex, it will significantly decrease the chance that you will get pregnant. Seven out of every 8 women who would have gotten pregnant will not become pregnant. Plan B® (levonorgestrel) works even better than this if taken within the first 24 hours after sex.

How will I know if Plan B® (levonorgestrel) worked?

Most women will have their next menstrual period at the expected time or within a week of the expected time. If your menstrual period is delayed beyond 1 week, you may be pregnant and you should get a pregnancy test and follow up with your healthcare professional.

What if I am already pregnant and use Plan B® (levonorgestrel) ?

There is no medical evidence that Plan B® (levonorgestrel) would harm a developing baby. If you take Plan B® (levonorgestrel) accidentally after you are already pregnant, or it does not work and you become pregnant, it is not likely to cause any harm to you or your pregnancy. Plan B® (levonorgestrel) should not have any effect on a pregnancy after implantation.

What should I do if my menstrual period is delayed beyond 1 week and I have severe lower stomach pain?

If you have severe lower stomach pain about 3 to 5 weeks after taking Plan B® (levonorgestrel) , you may have a pregnancy outside the uterus (a tubal pregnancy). See a healthcare professional right away because a tubal pregnancy requires immediate medical treatment.

Can I use Plan B® (levonorgestrel) for regular birth control?

Plan B® (levonorgestrel) should not be used for regular birth control. Plan B® (levonorgestrel) is not as effective as using a regular birth control method correctly and consistently. It is a backup method to be used if your regular birth control fails or if you have sex without birth control. You should not have unprotected sex following treatment because Plan B® (levonorgestrel) will not protect you from getting pregnant.

How often can I use Plan B® (levonorgestrel) ?

Plan B® (levonorgestrel) is meant for infrequent emergency protection. If you need to use emergency contraception often, you should consult with your healthcare professional for your best methods of birth control and STD prevention.

Will I experience any side effects from Plan B® (levonorgestrel) ?

When used as directed, Plan B® (levonorgestrel) is safe for women. Plan B® (levonorgestrel) has no serious or lasting medical side effects. Some women will experience non-serious side effects, such as nausea, stomach pain, headache, dizziness, or breast tenderness. These are similar to the side effects of regular birth control pills. Some women have menstrual changes such as spotting or bleeding before their next period. Some women may have a heavier or lighter next period, or a period that is early or late. If your period is more than a week late, you should get a pregnancy test.


Last reviewed on RxList: 5/24/2007
This monograph has been modified to include the generic and brand name in many instances.

Plan B - User Reviews

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