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Major Side Effects of Postinor-2 on Menstruation

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Postinor-2 side effects

Ever took Postinor-2 and your cycle became messed up? Well, that is one of the major side effects of Postinor-2 on menstruation. But that is not the only one.

Key points:

  • Postinor 2 is an important option for emergency contraception because it contains Levonorgestrel as the main synthetic hormone present, and which can have a side effect on menstruation.
  • Changes in menstrual flow and timing, menstrual cramps, breast tenderness, nausea, vomiting, and headaches are some of the common side effects that may occur after taking Postinor 2.
  • It is crucial to monitor for any changes or symptoms after taking Postinor 2 and seek medical advice if needed. Your healthcare provider can provide personalized guidance and management options based on your individual health history and needs.
  • It is also important to remember that Postinor 2 should not be used as a regular form of contraception but only as an emergency option when other contraceptive methods have failed or were not used. 

Everyone has experienced being caught in the rain without an umbrella at some point. Whether you left your house without one or the wind was so strong that it damaged the one you had, when you become exposed to rain, your next best option is to find a place of shelter.

In the same way, whether you engage in unprotected sex or experience contraceptive failure, the use of emergency contraception, such as Postinor-2, becomes an important option to prevent unintended pregnancies.

However, like any medication, postinor-2 may have potential side effects, including its impact on menstruation. Remarkably, almost 17% of women who took postinor-2 had notable changes in their menstrual cycles and the length of their menstrual bleeding. However, each individual may experience this adverse effect of postinor-2 differently. It is incredibly possible for some women to have their period one week earlier than others because we are all unique in our own way.

In this article, we discuss how Postinor-2 works, the potential side effects of Postinor-2 on menstruation, and when to contact your healthcare provider if you experience these side effects.

How does Postinor-2 work: Dosage and best time to take it

side effects of Postinor-2 on menstruation
Credit: Canva

Postinor-2 is a well-known emergency oral contraceptive, and it is also known as “morning after pill” or “day after pills.” Postinor-2 is a type of emergency contraceptive pill that contains levonorgestrel, a synthetic hormone that is used to prevent pregnancy after unprotected sex or contraceptive failure, such as a condom breakage or missed birth control pills.

Postinor 2 works primarily by preventing or delaying ovulation (the release of an egg from the ovary), to reduce the chances of fertilization by sperm. 

It is taken orally. The two tablets are usually taken together.

It is most effective when taken as soon as possible after unprotected sex, preferably within 72 hours (3 days).  When used within 5 days after intercourse, it can still prevent up to 95% of pregnancies. 

However, it is not intended for regular use and should only be used in emergency situations. It should not be used more than once during your menstrual cycle. If you are concerned about the possibility of an unplanned pregnancy, then take advantage of postinor-2 pills as soon as you can; the earlier you take the pills the better. 

Other forms of contraception appropriate for long term use include condoms, oral contraceptive pills, and intrauterine devices (IUDs).

It is also important to note that while Postinor-2 may prevent unintended pregnancies, it does not protect against sexually transmitted infections, including the human immunodeficiency virus (HIV) and hepatitis B.

Postinor-2 is generally considered safe and effective, but like any medication, it has potential side effects. 

The most common side effects of Postinor-2 on menstruation can be related to the hormonal changes it can cause. It is crucial to understand the potential aftereffects of Postinor-2 on menstruation in order to make informed decisions when considering its use.

3 Major Side Effects of Postinor-2 on Menstruation

side effects of Postinor-2 on menstruation
Credit: Canva

1. Changes in Timing:

The side effects of postinor-2 on menstruation can be witnessed in its potential disruption of the normal menstrual cycle. Some females may experience irregular periods where the timing of their menstrual bleeding is altered.

This can include periods that come earlier or later than expected or even skipped periods. The hormonal changes caused by Postinor 2 can interfere with the normal hormonal fluctuations that regulate the menstrual cycle, leading to these disruptions.

2. Changes in flow:

In addition to changes in timing, side effects of postinor-2 on menstruation can be experienced in the flow of menstrual periods. 

Some women may experience heavier or lighter menstrual bleeding than usual after taking Postinor-2. These changes in menstrual flow are usually temporary and return to normal in a few menstrual cycles.

3. Spotting:

Postinor 2 can also cause spotting or breakthrough bleeding, which refers to light bleeding or spotting between menstrual periods.


Other side effects of Postinor-2

In addition to the above, Postinor 2 may also cause other symptoms related to menstruation. These symptoms may vary from person to person and may include:

  1. Menstrual Cramps: Some women may experience increased menstrual cramps or abdominal pain after taking Postinor 2. These cramps can be mild to severe and may last for a few days.
  1. Breast Tenderness: Postinor 2 can also cause breast tenderness or sensitivity in some women. The hormonal changes caused by Postinor 2 can affect the breast tissue and lead to discomfort or pain.

Other effects include headaches, nausea, vomiting, and less commonly, diarrhea. However, your menstrual cycles can be influenced by a number of things, such as food, certain drugs, stress, and hormonal changes. For the reasons highlighted above, the morning-after pill may not be the only reason for your delayed period.

When to talk to a doctor 

Postinor-2 side effects
Credit: Canva

While most side effects of Postinor 2 on menstruation are temporary and resolve on their own, there are certain situations where it’s important to seek medical advice promptly. Here are some circumstances in which you should talk to a doctor:

1. Severe or Persistent Symptoms:

If you experience severe or persistent symptoms, such as heavy or prolonged bleeding, severe menstrual cramps, persistent breast tenderness, or persistent nausea and vomiting after taking Postinor 2, it’s important to contact your healthcare provider promptly.

These symptoms may require further evaluation and management.

2. Concerns about Pregnancy: 

Postinor-2 is not 100% effective, and there is a possibility of pregnancy even after taking the medication.

So, if you suspect that you may be pregnant despite taking the medication, it’s important to contact your healthcare provider for further evaluation. Your healthcare provider will perform a pregnancy test and provide appropriate guidance based on the results.

3. Persistent Changes in Menstrual Flow:

If you notice persistent changes in your menstrual flow, even after a few menstrual cycles, it’s important to contact a doctor for evaluation.

These changes may require further investigation to determine the underlying cause and appropriate management.

Postinor-2 and other medications

Inform your healthcare professional or pharmacist of any additional medications you are taking or have taken recently, including over-the-counter and herbal remedies. The reason has been that certain medications may hinder the ability of Postinor-2 to function as intended.

Also, postinor-2 might not be effective for you if any of the medications called liver enzyme inducers listed below have been taken in the last four weeks:

  • Barbiturates and other epilepsy medications (such as carbamazepine, phenytoin, and primidone)
  • Drugs for tuberculosis (such as rifampicin and rifabutin).
  • Herbal medicine with Hypericum perforatum.
  • HIV treatment drugs (ritonavir, efavirenz).

4. General Concerns or Questions:

If you have any general concerns or questions about the side effects of Postinor 2 on menstruation or its overall impact on your health, it’s always advisable to speak with a certified gynecologist.

He/she can provide accurate information, address your concerns, and provide appropriate guidance based on your individual health needs. 

Frequently asked questions

  1. Do adverse effects from Postinor-2 include delayed menstruation?

Delay in your next menstruation cycle is one of the side effects of postinor-2. The side effects of postinor-2 on menstruation extend to the changes in bleeding during your periods. Take note that menstruation cycles that are either early or delayed are frequently caused by disruptions to the menstrual cycle. Therefore, seeing a medical practitioner is advised, as there are other potential causes of delayed menstruation.

2. To what extent does Postinor-2 delay pregnancy? 

The best results from Postinor-2 come from taking it right away following unprotected sexual activity. If taken within 24 hours, it can lower the risk of pregnancy by as much as 95%. Though its potency diminishes with time, it is advised to take it no later than 72 hours (3 days) following unprotected intercourse.

3. Why are periods delayed by postinor-2?

Levonorgestrel is the main active synthetic hormone present in postinor-2, and that can contribute to the side effects of on postinor-2 on menstruation. Your regular menstrual cycle can be altered by the hormonal changes initiated by postinor-2. Individual reactions, however, could differ.

4. Is vaginal bleeding normal after taking Postinor 2?

An emergency pill such as Postinor-2 may cause slight bleeding in some women as a side effect of postinor-2 on menstruation, and it normally stops within 3 days. However, watch out for heavy bleeding that lasts for more than 3 days, as it may be an indication of a problem. Ensure you contact your gynaecologist instantly if you experience heavy vaginal bleeding that lasts more than 3 days, because it is one of the side effects of postinor-2 on menstruation.

5. How frequently can I use Postinor 2?

Postinor 2 should not be used as a normal form of contraception; rather, it should only be used in emergencies such as sexual assault, failed contraception (displaced condom or diaphragm), consensual intercourse without the use of contraception, and discharge of semen on the external genitalia. You should also know that Postinor 2 is not reliable and is more likely to disrupt your menstrual cycle (period) if it is used more than once during a menstrual cycle.

It is obvious that Postinor 2 is not as effective as conventional forms of birth control. Speak to a healthcare professional about other efficient, long-term contraceptive methods that will work best for you.

6. What happens if I use too much Postinor 2?

Postinor 2 works best within 72 hours of engaging in unprotected intercourse, and it offers a simple way to prevent abortions. Nonetheless, taking more than the prescribed dosage of Postinor 2 can exacerbate the risks of exposure to side effects such as imbalances in your hormones, distorted menstrual bleeding, and short-term hormonal disruptions. Adhere to the dosage instructions on Postinor 2 for optimal health benefits.

7. What are the side effects of Postinor 2 after a week?

There are some frequent and temporary side effects that you may experience within 7 days of taking Postinor 2, and they include delay or heavier menstrual bleeding, vomiting, abdominal cramps, headaches, nausea, dizziness, fatigue, and breast tenderness. Do not be wary of these side effects because they subside or sort out on their own.

8. What should I do when my period is delayed after taking postinor-2?

You can experience side effects of postinor-2 on menstruation by noticing a delay in your period, but there can be other possible causes as well. Even if the postinor-2 successfully inhibits conception, there is a remote possibility of conception happening. It is advisable to schedule an appointment with your gynaecologist when you experience a side effect of postinor-2 on your menstruation. This is so the doctor may examine you.

Some tests will be conducted, including a pregnancy test. If the pregnancy test results are negative and you are still not getting your period, then the doctor will order a blood test to measure your placenta’s released hormone, called beta-hCG, and ascertain the status of your body.

Your doctor will provide you with guidance, considering your unique circumstances.

Note that your doctor’s consultation can be through video calls, and the recommended tests can be prescribed and sent electronically. Through telemedicine, all your healthcare needs are met. Consult a Doctor on KompleteCare.


Okeke, G. O. (2023). Irregular periods (menstruation): causes and home remedies to regulate your cycle.

Okeke, G. O. (2023). Emergency contraception: A solution or a problem.

Oyetunji, T. (2023). Side effects of postinor-2 on menstruation.

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Dr. Temitope Oyetunji is a family physician with years of clinical practice experience. She is passionate about using clear, understandable written and video content to disseminate health information.

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