Does Plan B affect your period?

In this article:

• Does Plan B affect your period?
• What you might experience after taking Plan B
• What can you expect for your first period after taking the morning-after pill?
• What does Plan B not do?
• Where can I get Plan B?
• What are other types of birth control?
• When to consult a healthcare professional

In this article

• Does Plan B affect your period?
• What you might experience after taking Plan B
• What can you expect for your first period after taking the morning-after pill?
• What does Plan B not do?
• Where can I get Plan B?
• What are other types of birth control?
• When to consult a healthcare professional

Plan B One-Step, or Plan B, is a type of medication used as an emergency contraceptive drug or emergency birth control. Commonly referred to as EC or the morning-after pill, it can be used to prevent pregnancy after having unprotected sex or birth control failure—for example, if:

• A condom breaks
• A diaphragm moves out of place
• You forget to take birth control pills
• You do not use birth control during sex
• You use birth control incorrectly
• You have been sexually assaulted or raped

Plan B contains the active ingredient levonorgestrel, a type of progesterone hormone. Taken as directed, this form of emergency contraception is effective in lowering the risk of unplanned pregnancy—and generally well-tolerated, although mild side effects are possible. Many women ask if Plan B will affect their menstrual cycle. The short answer is that taking Plan B may affect your next menstrual cycle length or bleeding—for example, you may have an early or late period, or the bleeding may be lighter or heavier.

Does Plan B affect your period?

Yes, Plan B can affect your period. After taking Plan B, your next period may be normal, or it may come earlier or later. The period length and type of bleeding may be different, too—it may be spotty, lighter, or heavier than usual. If, however, you are one week or more past your expected period start date and do not yet have your period, you should take a home pregnancy test (or take a test at your healthcare provider’s office) to see if you are pregnant.

Plan B contains levonorgestrel, a progesterone hormone. As an emergency contraceptive pill, Plan B works by preventing or delaying ovulation. Ovulation is the time in your cycle, generally mid-cycle, when an egg is released from the ovary, travels down the fallopian tube, and is ready to be fertilized and begin a pregnancy. Plan B does not work if ovulation has already occurred or if you are already pregnant.

Plan B is very effective. Morning-after pills that contain the hormone levonorgestrel, such as Plan B, Take Action, My Way, My Choice, Aftera, or EContra One-Step, are most effective if taken as soon as possible after unprotected sex. The sooner you take Plan B, the better it will work. If taken within three days (72 hours) of unprotected sex, Plan B can lower the chance of pregnancy by 75 to 89%. However, it can still work up to 5 days (120 hours) after unprotected sex—but is not as effective as if you take it sooner.

What you might experience after taking Plan B

In addition to temporary changes in your menstrual cycle, you may experience some other mild common side effects after taking Plan B, such as:

• Headache
• Upset stomach
• Nausea and vomiting (If you throw up within two hours of taking Plan B, you should ask a healthcare provider if you need to take another dose.)
• Dizziness or lightheadedness
• Breast tenderness
• Tiredness

There are not any serious side effects associated with taking Plan B.

What can you expect for your first period after taking the morning-after pill?

Your next period may be on time and completely normal, or it may be one or a combination of the following types of irregular bleeding:

• Earlier than usual
• Later than usual (delayed period)
• Spotty
• Lighter than usual
• Heavier than usual
• Shorter than usual
• Longer than usual

Keep in mind that if your period is more than a week late, you should take a pregnancy test.

Research has shown that most menstrual changes disappear after the first period following a dose of Plan B. 

What does Plan B not do?

Because it can be confusing, what are some things Plan B is not or does not do?

• Plan B is not an abortion pill
• Plan B will not work if you are already pregnant
• Plan B does not protect against sexually transmitted infections such as HIV and AIDS

Plan B should not be used as a regular form of birth control. Although you can use emergency contraception (EC) more than once in a cycle, using EC often may cause more side effects as well as irregular periods. Other forms of birth control are much more effective when used correctly and consistently. You can talk to your healthcare provider about the best type of birth control for you.

Where can I get Plan B?

Now, it is easier than ever to get Plan B. You do not need a prescription, and you do not have to show identification. Anyone of any age can buy Plan B over the counter at a pharmacy. You may also find Plan B at your local family planning clinic, Planned Parenthood location, or local health department. 

What are other types of birth control?

You may want to consider a form of birth control that you can use on a regular basis to prevent pregnancy. There are many factors to consider when choosing the best form of effective birth control, such as preferences on how you take or use it, how long you want the birth control to last, and others. Although they can all prevent pregnancy, only the male condom or female condom can also prevent sexually transmitted infections. Some examples of birth control include:

• Short-acting hormonal birth control: this includes birth control pills, patches, shots, or vaginal rings
• Long-acting reversible contraceptives (LARC): these include intrauterine devices (IUDs) and hormonal implants, which are inserted by a health care provider and can last anywhere from 3 to 10 years, depending on which LARC you use.
• Barrier methods: condoms, diaphragms, sponge, cervical cap; these are required each time you have sex
• Sterilization: This is a type of birth control that is used for lifelong pregnancy prevention through surgery, such as female tubal ligation or male vasectomy.

Consult your healthcare professional with questions and for more information and medical advice on birth control.

When to consult a healthcare professional

After taking Plan B, you should take a pregnancy test if your period is late by a week or more. You can take a home pregnancy test or see a healthcare provider. 

Also, suppose you have symptoms of severe lower abdominal pain 3 to 5 weeks after taking Plan B. In that case, you should see your doctor for immediate medical attention to be evaluated for an ectopic pregnancy (pregnancy outside of the uterus). 

If you take Plan B once during your cycle, your next period may be irregular; then, it will return to normal with the following cycle. However, if you take Plan B more often, there is a higher chance of having irregular periods. You can talk to your healthcare professional about regular forms of birth control. As a bonus, many of them make your periods more regular (and lighter) and have other benefits such as less menstrual cramps, clear skin, and lower risk of endometrial and ovarian cancer.