Plan B One-Step is a type of emergency contraception. This is birth control that can prevent pregnancy after unprotected sex. People sometimes call it the "morning after pill." But you don't have to wait until the morning after sex to take it. In fact, Plan B is more effective the sooner you take it. It is a one-dose regimen: you take one pill. The pill contains 1.5 milligrams of levonorgestrel, which is used in lower doses in many birth control pills.
How Does Plan B One-Step Work?
Depending upon where you are in your cycle, Plan B One-Step may work in one of these ways:
- It may prevent or delay ovulation.
- It may interfere with fertilization of an egg.
It is also possible that this type of emergency birth control prevents implantation of a fertilized egg in the uterus by altering its lining.
Plan B One-Step is not the same as RU-486, which is an abortion pill. It does not cause a miscarriage or abortion. In other words, it does not stop development of a fetus once the fertilized egg implants in the uterus. So it will not work if you are already pregnant when you take it.
How Effective Is Plan B One-Step?
If you take it within 72 hours after you've had unprotected sex, Plan B One-Step can reduce the risk of pregnancy by up to 89%. If you take Plan B One-Step within 24 hours, it is about 95% effective.
But you should know that Plan B One-Step is not as effective as regular contraception. So don't take it as your main form of birth control. And, it does not protect you against sexually transmitted diseases. Think of it as a backup -- not for routine use. That's why it's called Plan B.
Also, research shows that Plan B One-Step starts to lose its effectiveness in women heavier than 165 pounds and is not recommend for anyone over this weight.
How to Take Plan B One-Step
Plan B One-Step can be purchased over the counter at drugstores without a prescription or proof of age. Because it is most effective when taken as soon as possible (up to 72 hours after sex), consider having a ready supply in your medicine cabinet. Better yet, use a reliable form of birth control.
You can take Plan B One-Step if:
- You didn't use any birth control.
- The condom came off or broke.
- The diaphragm slipped out of place.
- You missed at least two or three active birth control pills in a row.
- You forgot to insert your ring or apply your patch.
- Your partner didn't pull out in time.
- You have another reason to think your birth control might not have worked.
- You were forced to have sex.
Remember: Plan B One-Step will not protect you from getting pregnant if you have sex after taking the pills. Instead, you need to take it right after you have unprotected sex.
Do not take Plan B One-Step if:
- You know you are pregnant or suspect you might be.
- You have a history of allergy or hypersensitivity to its ingredients.
- You have a history of recent abnormal vaginal bleeding that your doctor has not yet evaluated.
- You weigh over 165 pounds.
Side Effects of Plan B One-Step
Many women have taken emergency contraception without serious complications. But it's a good idea to ask your doctor about possible interactions with other medications.
Plan B One-Step is considered safe for most women. You should not take it if you are pregnant because it will not end the pregnancy.
Potential side effects of Plan B One-Step include:
If you vomit within two hours after taking the drug, call a healthcare professional to find out if you should repeat the dose.
With Plan B One-Step, you may also have some unexpected bleeding. It should go away by the time of your next period. However, it is possible that Plan B One-Step may cause your next period to be heavier or lighter than usual. It may also come earlier or later than is normal for you. If you don't get your period within three weeks, get a pregnancy test to make sure you're not pregnant.