You may experience bleeding or spotting after taking Plan B. Some people may also experience temporary changes to their menstrual cycle.

Plan B One-Step is a brand of over-the-counter (OTC) emergency contraception. You can use it as a backup if you suspect your birth control may have failed, you missed taking a birth control pill, or if you had unprotected intercourse.

It’s not common, but Plan B can lead to unexpected spotting and bleeding. According to the package insert, Plan B can cause other changes to your period, such as heavier or lighter bleeding or getting your period earlier or later than normal.

This type of bleeding after taking Plan B isn’t generally a cause for concern.

Keep reading to learn more about bleeding associated with Plan B, plus signs that you should seek medical care.

Plan B works by delaying ovulation so the sperm and the egg never meet. If you’ve already ovulated, it may prevent fertilization or implantation of a fertilized egg.

What’s in it?

Plan B contains a progestin called levonorgestrel. It’s the same hormone used in oral contraceptives, but in a single, higher dose. It causes a change in hormone levels, which can affect the usual pattern of your menstrual cycle.

This can lead to spotting between the time you take it and the beginning of your next period. It can also cause your period to start up to a week earlier or a week later than you would otherwise expect. Your first period after taking Plan B could be somewhat lighter or heavier than is normal for you.

Everyone is different, so some people will have spotting and bleeding before their next period and some won’t. There’s no way to know in advance how your body will react to the increase in hormones.

How often can I take it?

You can take Plan B as often as you need to, but the more you take it, the more likely you are to have spotting and menstrual irregularities. If you find yourself needing Plan B often, talk to your doctor about other methods of birth control that may be more effective.

Plan B doesn’t cause miscarriage and isn’t an abortion pill. You shouldn’t have the type of heavy blood flow that contains large clots.

Could I be pregnant?

Some spotting after using Plan B is harmless. It shouldn’t be taken as a sure sign that you’re not pregnant, though.

Implantation spotting can happen when a fertilized egg attaches to the lining of the uterus. This is perfectly normal in early pregnancy, usually occurring about 10 to 14 days after conception.

You’ll only know that you’re not pregnant when you get your period or have a negative pregnancy test.

In addition to spotting and menstrual changes, other potential side effects from Plan B may include:

  • nausea
  • lower abdominal cramps
  • feeling tired
  • headache
  • dizziness
  • breast tenderness
  • vomiting

If they happen at all, these side effects should only last a few days and you probably won’t have all of them.

Emergency contraceptive pills are not associated with serious or long-term side effects. Plan B won’t affect your ability to get pregnant or carry a pregnancy in the future.

Remember, your period may be late even if you’re not pregnant.

You don’t have to do anything for spotting, getting your period early, or a heavier-than-normal period. When you take Plan B, keep some menstrual products on hand just in case.

Your cycle should return to normal the following month.

The sooner you take Plan B, the more likely it is to be effective. Ideally, it should be taken within a 72-hour window. That’s 3 days from the time you had unprotected sex. You should also continue to use your regular birth control.

In any case, it’s not 100 percent effective. It’s estimated that about 7 of every 8 women who would have gotten pregnant will not get pregnant after taking the medication. It may not work if you vomit within 2 hours of taking it.

Take a test

When you haven’t gotten your period within 4 weeks of taking Plan B, take a home pregnancy test.

If you get a negative result, wait 2 more weeks. If you still haven’t started your period, take another pregnancy test. If you get another negative result, see your doctor to determine why you’re not having a period.

If the test is positive

If your pregnancy test is positive, it’s still a good idea to see your doctor to confirm the results. It’s also an opportunity to begin a discussion about your options. If you’re pregnant and want to continue the pregnancy, you’ll be able to get started on prenatal care right away.

If you decide that you don’t want to continue with the pregnancy, your doctor can explain the different types of abortion available to you.

Alternatively, you can contact the nearest Planned Parenthood clinic to learn more. Legal options vary depending on where you live. The Guttmacher Institute provides the latest information about abortion laws in each state.

Plan B is an OTC medication. You can get it at most drugstores without seeing a doctor or getting a prescription.

Before taking Plan B

Although this type of emergency contraception is often called “the morning-after pill,” you definitely don’t need to wait until morning to take it.

It also makes no difference where you are in your menstrual cycle. The important thing to know is that the sooner you take it, the better the chance that it will work.

Certain medications can make Plan B less effective. You’ll want to talk to your doctor or pharmacist before taking Plan B if you currently take:

  • barbiturates
  • medications to treat HIV, tuberculosis, or seizures
  • the herbal supplement St. John’s wort

If you take any of these or if you ever had an allergic reaction to levonorgestrel, see your doctor as soon as possible. Time is of the essence, but there are alternative methods of emergency contraception they can recommend.

Plan B isn’t meant to be used as a regular form of birth control. If you don’t have a birth control method you feel good about, your doctor can help you choose something else. Keep in mind that emergency contraception offers no protection from sexually transmitted infections (STIs).

After using Plan B

Most people don’t need to see a doctor after taking Plan B. Side effects are temporary and you should be back to normal soon. Do contact your doctor if:

  • You vomited within 2 hours of taking Plan B and want to know if you should take another dose.
  • It’s been more than 4 weeks since you took Plan B and you haven’t had a period or a positive pregnancy test.
  • You have very heavy bleeding that shows no sign of slowing down after several days.
  • You’ve been spotting or bleeding longer than a week and also have lower abdominal pain or dizziness.
  • You have severe abdominal pain. This could indicate an ectopic pregnancy, a potentially life-threatening event.
  • You think you’re pregnant and want to discuss the next steps.

Plan B is a safe and effective way to lower your chances of becoming pregnant after having unprotected sex. It can cause unexpected spotting, bleeding, and menstrual irregularities, but these side effects are temporary.

Heavy bleeding accompanied by other symptoms could be a sign that something more serious is going on. Check in with your doctor if you’re concerned.