Plan B is an emergency contraceptive than can be taken after unprotected sex or after a chosen form of birth control has failed to prevent unwanted pregnancy, making it a highly desirable birth control method but also a controversial one. We talked a little bit about what Plan B is and why you may consider taking it in another article but for this one, we’re just going to focus on the potential side effects of these pills so you can make an informed decision as to whether or not this is the right option for you.

What Are the Most Common Plan B Side Effects? (Side Effects of The Morning After Pill)

As with any medication, there are Plan B side effects you should be aware of before you consider taking it. Not every woman will experience these side effects but it is still important to know any potential problems you may encounter after you take your pills. Some of the most common Plan B side effects are:

  • Headache
  • Nausea
  • Fatigue
  • A change in your menstrual flow (either heavier or lighter)
  • Dizziness or lightheadedness
  • Tenderness in the breasts

Most of the symptoms women encounter after taking Plan B are mild and don’t require any sort of medical attention. They last a fairly short amount of time during which the woman is able to go about her normal day to day activities. Although most women will still get their period on time, some women will in fact find their period is delayed for a few days. It’s important to keep this in mind as, obviously, a late period is one of the most recognized pregnancy symptoms. Because Plan B is not 100% effective though, it is important to make sure you take a pregnancy test if your period is more than a few days late. You may be pregnant and if you are, you’ll want to find out as soon as possible to weigh your options and take action based on your choice.

What Are Some Less Common Plan B Side Effects?

Having already talked about what Plan B side effects you can expect to experience after taking the pills, it’s important to get into some of the less common, more serious Plan B side effects that have been noted. At this point though, I’d like to remind you that these side effects are uncommon and few women who take the pills will experience them. Some less common Plan B side effects include:

  • Diarrhea
  • Migraine
  • Vomiting
  • Late periods
  • Allergic reaction
  • Severe abdominal pain
  • Ectopic pregnancy

Clearly all of these side effects are far more severe than the ones we talked about in the section above and while they are more rare, they are possibilities you need to be prepared for. Of all of them, the ectopic pregnancy is clearly the most worrisome. An ectopic pregnancy takes place when a woman’s egg is fertilized by a man’s sperm but instead of the fertilized egg implanting itself in the uterus, it implants itself in another location. Ectopic pregnancies can be life threatening but there are treatments available for ectopic pregnancies and the success rate for those treatments are as high as 94%.

When Should I See My Doctor About Plan B Side Effects?

In the vast majority of cases, woman who experience side effects after taking Plan B will not need to seek medical attention. As I mentioned a few moments ago, most Plan B side effects are mild and can mostly be ignored. There are times when that isn’t true though. If you experience severe cramping in your stomach or pelvic region, you may have an ectopic pregnancy and you will need to make an appointment with your doctor immediately. While these pregnancies can be treated and the success rate of those treatments is significant, the success rate lowers the longer you wait. Don’t gamble with your health. There could be absolutely nothing wrong but it always better to be safe than sorry.

Beyond abdominal cramps and symptoms of an ectopic pregnancy, you also need to see a doctor if you present with symptoms of an allergic reaction. Symptoms of an allergic reaction include:

  • Skin rash
  • Itchiness
  • Swelling
  • Labored breathing or wheezing
  • Hives
  • Trouble swallowing

Allergic reactions can be severe but like with ectopic pregnancies, they can be treated. If you seek help immediately, the chances of making a full recovery are in your favor. The longer you wait, the more severe the reaction could become, sometimes leaving you with permanent damage or possibly even creating a life threatening condition.

Plan B Side Effects: The Statistics

Most women who take Plan B will experience at least one of the more common Plan B side effects. There are women who will experience none and women who will experience all of them. Making an informed decision means knowing what you could potentially be in for. To make the information a little clearer, I’ve decided to include the statistics for many of the more common and some of the uncommon Plan B side effects.

  • 23.1% of women who took Plan B experienced minor nausea.
  • 17.6% of women who took Plan B experienced minor abdominal pain.
  • 16.9% of women who took Plan B experienced fatigue.
  • 16.8% of women who took Plan B experienced minor headaches.
  • 13.8% of women who took Plan B experienced a heavier than usual menstrual flow.
  • 12.5% of women who took Plan B experienced a lighter than usual menstrual flow.
  • 11.2% of women who took Plan B experienced dizziness or lightheadedness.
  • 10.7% of women who took Plan B experienced tenderness in their breasts.
  • 5.6% of women who took Plan B experienced vomiting.
  • 5% of women who took Plan B experienced diarrhea.

As of right now, there are no statistics available on the more serious side effects we spoke of a moment ago, but all of those more serious side effects were observed less frequently than any of the side effects listed above. It is important to mention there is now a single dose Plan B option available on the market that works basically the same way as the traditional two dose version but has different statistics as far as side effects go. The statistics for Plan B side effects associated with the newer, single dose version are as follows:

  • 30.9% of women who took single dose Plan B experienced a heavier than usual menstrual flow.
  • 13.7% of women who took single dose Plan B experienced minor nausea.
  • 13.3% of women who took single dose Plan B experienced abdominal pain.
  • 13.3% of women who took single dose Plan B experienced fatigue.
  • 10.3% of women who took single dose Plan B experienced minor headaches.
  • 9.6% of women who took single dose Plan B experienced dizziness or lightheadedness.
  • 8.2% of women who took single dose Plan B experienced tenderness in their breasts.
  • 4.6% of women who took single dose Plan B experienced a later than usual menstrual cycle.

If you aren’t sure what side effects you may experience or are concerned about how Plan B will work for you, discuss the option with your doctor. Your doctor will be able to offer you the best possible medical advice and will help you decide whether or not Plan B is the best option for you.


Plan B One-Step is an emergency contraception. This kind of birth control prevents pregnancy after having unprotected sex. It is more commonly known as ‘morning after pill.’ However, you don’t have to wait until the morning after sex for taking it. Studies indicate that Plan B is more effective the sooner you take it after a sexual intercourse. The birth control method is a one-dose regimen. Each pill consists of 1.5 milligrams of levonorgestrel that is frequently used in lower doses in various other birth control pills.

How Effective Is Plan B?

If Plan B is taken within 72 hours after an unprotected sex, it reduces the risk of pregnancy by up to 89%. However, if you take Plan B One-Step within 24 hours, it is shown to product positive results up to 95%. Some incidents also reveal that the use of Plan B may still work successfully on the fifth day (depending on your menstrual cycle).

Women must be aware of the fact that Plan B One-Step should not be considered as a regular contraception method to prevent pregnancies. As the name suggests, it should serve as a backup plan in case you have an unplanned sexual contact. It does not protect against STD’s, therefore, the contraceptive method is not ideal for routine use.

How Does Plan B One-Step Work

Plan B One-Step works in any one of these ways, depending on where you are in your cycle:

  • It delays or prevents ovulation
  • It interferes with the egg fertilization process
  • It is also possible that it prevents the implantation of a fertilized egg in the uterus

It should also be noted that Plan B does not work the same way as RU-486, which is an abortion pill and will not result in an abortion or miscarriage. Simply put, the pill is not capable of stopping the developing of a fetus if the fertilized egg has managed to plant itself in the uterus. This implies that the pill has no effect if you are already pregnant.

How to Take Plan B

All women should use Plan B exactly according to the directions that are listed on its label. If it has been prescribed by a doctor, then follow the recommended dosage and do not over use it. In an ideal situation, it should be taken as soon as possible after an unprotected sexual intercourse to prevent an unwanted pregnancy. It should not be used later than 72 hours. The second dose should be taken 12 hours following the first dose.

Contact your doctor immediately if you throw up within 1 hour of swallowing the pill. It is recommended that no further dosages should be administered without discussing with your doctor. In order to make sure that no harmful effects are caused by the pill and no pregnancy has taken place, you can also get yourself examined after three weeks of using Plan B. Note that if your period is a week late or longer than your usual date, a pregnancy may have occurred. You can take a pregnancy test or contact your doctor to know if you have become pregnant.

Once the fertilized egg is attached to the uterus, Plan B will have no effect on preventing the pregnancy, as it is not an abortion pill. Plan B should be stored at room temperature and kept safe from heat and moisture.

What Happens If You Miss A Dose?

The timing of a dose is important as if you miss a dose, the chances of becoming pregnant increases.

What about an Overdose

Overdose symptoms are characterized by extreme nausea and vomiting. Call your doctor immediately if you think you have over-dosed on Plan B.

Does It Protect From STDs?

Since Plan B has no effects on protecting an individual from acquiring a sexually transmitted disease (including AIDS and HIV), it is not considered better than using a condom. The only way to guard yourself again STD’s is to avoid having unprotected sex or without a condom.

Interaction with Other Drugs

If you are on other drugs, make sure you consult your doctor to know whether you can use Plan B. Some of these drugs include:

  • Rifampin
  • Amobarbital, Butabarbital, Mephobarbital, Secobarbital, Or Phenobarbital
  • Seizure Medicines Such As Phenytoin Or Carbamazepine

This list may extend to some other drugs that can interfere negatively with Plan B. Certain Over the counter medicines, supplements, minerals and herbal products can affect how Plan B works inside your body.

Side-Effects of Plan B

Much has been written and tested on the side effects that accompany with the use of Plan B. Thousands of women have successfully benefited from this emergency contraception method without facing any major complications. However, it is always recommended that you consult your doctor about possible harms that the pill can cause in an individual case.

Even though Plan B One-Step is deemed safe for most women, this article aims to shed light on the side effects that it can have.

Potential side effects:

  • Fatigue
  • Headache
  • Dizziness
  • Nausea
  • Abdominal Pain
  • Breast Tenderness
  • Vomiting
  • Menstrual Changes

If anyone vomits after two hours of administering the pill, a doctor should find out if the dosage could be repeated again.

Some women may also experience some unexpected bleeding after taking the pill. This should subside by the time your next period is due. There is a possibility that the contraceptive pill can cause your next period to be lighter or heavier than your previous one. Almost one-third of women may observe that their periods are heavier than usual, after taking Plan B. Moreover, around 10 percent of women may experience discomfort from breast tenderness.

Using this pill can also lead to a fluctuation of dates for your next period. In case a woman does not get her period within three weeks of using the pill, a pregnancy test should be taken to know if she has become pregnant or a healthcare practitioner must be contacted.

Weight Factor

Plan B has shown relatively less effective results for women who exceed the 75 kg weight mark. This implies that if a woman weighs more than this limit (165 pounds) then the pill will not as effective as it is for women who weigh less. If your weight is beyond 80 kg, (176 pounds) then contact your doctor for inquiring whether Plan B will be an effective birth control measure to prevent a pregnancy

More Side-Effects

Hormone-Related Side Effects

As Plan B is itself a hormone, it is only natural that a few of its side effects are related to the hormone system or the endocrine. Women who take Plan B are likely to wait for later than their usual date for their next periods to take place.

Digestive Side Effects

One of the most common side effects of Plan B is nausea. Researches reveal that between 14% – 23% of women experience nausea as an annoying side effect of the pill. There may also be considerable abdominal pain or lower abdominal discomfort. Some women also complain of headaches within the initial days of using Plan B. Moreover, fatigue can make the headaches worse. Dizziness may also be another side effect that is also listed on the official website of the product.

Finally, dizziness is another side effect that is listed on the Plan B website. There are around 10% of women who use the morning-after pill that deal with this issue. If you experience any unusual side effects that are not listed, then contact your doctor immediately to check whether you are having symptoms of another serious medical condition, while using this pill.


Even though a few women have experienced loss of blood glucose control while administering progestin-only pills, it is important that women who have diabetes must monitor their blood glucose level closely after using this pill.

Liver Health

It is not yet confirmed whether the birth control method is safe to use if you have a liver disease. Discuss with your doctor whether you should take this pill in case you have experienced any significant liver health concerns for monitoring the effects of this drug.


Several women have complained of severe headaches or even migraine after taking a dose of levonorgestrel. This is a common side effect that surfaces after the use of Plan B.


Little amounts of progestin are transported into the breast milk of women who take progestin-only pills. However, there are no adverse effects on the quality of milk or infant development that have been verified due to the use of this medication while breast-feeding.


According to a publication, Plan B does not interfere with a woman’s capability to conceive and become pregnant in the future. However, they should not b used as a regular method of birth control and condoms or birth control pills should be adopted for long-term use.

Menstrual Changes

It is also observed that some women experience light spotting after using Plan B, which is sometimes mistaken for a menstrual period. However, this spotting takes place soon after taking Plan B and is not a period.  A large percentage of women who use Plan B will get their period at the usual date or may be a bit early. Whereas, a small percentage can have their periods delayed.

Always remember that Plan B is not ideal for regular use and is not a substitute for regular birth control pills. If somebody feels that there is a need for a more frequent use, then a more reliable contraception method should be used.

Pregnancy-like Symptoms

A surprising fact about Plan B is that some of its side effects may actually mimic several pregnancy symptoms. Vomiting, nausea, cramps, sore breasts, abdominal discomfort and headaches are all symptoms that are experienced when women conceive. Since the pill can also cause the next menstruation cycle to occur later than usual, some women eventually feel that they have become pregnant and the pill hasn’t worked.

However, this is not the case. Even though, these side effects lead women to believe that Plan B did not work for them, it usually results in preventing an unwanted pregnancy.

What If You Get Pregnant Despite Taking Plan B

Studies reveal that that there are no pregnancy complications or an increase in birth defects even after you get pregnant after using Plan B.

Warnings and Precautions of Using Plan B

Some more signs can indicate whether Plan has not worked to its fullest.  A light period, which is a week or more late, can signal that a pregnancy has taken place. A small percentage of women experience other signs that may be pointing out to a pregnancy. Sore or enlarged breasts, fatigue, nausea, headaches and frequent urination can also indicate a pregnancy.

Like any other birth control method, it is important that you should inform your doctor before using Plan B. This is crucial as you can reduce the risks of an allergic reaction to the pill. Other factors that must be taken into consideration before using it include breast-feeding, the use of other medications and being already pregnant.

This medication should not be given to anyone who is younger than 17 years old. Plan B can be used to prevent a pregnancy if a woman feels there are other issues such as a condom breakage or missing doses of birth control pills.

Effects on Existing Pregnancy

The pill is not designed to terminate a pregnancy that has already been in progress. Therefore, it should not be used in an attempt to cause an abortion or miscarriage. As the hormones in Plan B influence ovulation, the uterine lining and the cervical mucus, it is incapable of causing an abortion.

Other Considerations

A few factors that increase the likelihood of becoming pregnant even after taking the contraceptive pill, is the time a woman takes to use Plan B after an unprotected sexual intercourse. It is also noted that if a woman vomits after taking the pill, she is more likely to become pregnant as the body fails to absorb the medication completely.