Half dressed black lady in bathroom smiling at getting better understanding of how Postinor 2 works
05/11/2021 By AskAwayHealth

22 Most Common Questions About Taking Postinor 2 Effectively

Are you wondering about taking Postinor 2 and how to know if it works? How should you take Postinor 2? Does it affect your periods and fertility?

This post answers twenty-two common questions we encounter about taking this emergency contraception pill.



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What Type of Drug is Postinor 2?

Postinor 2 is a set of two emergency contraceptive tablets containing Levonorgestrel, a synthetic progesterone hormone.

Each tablet contains 750 micrograms of Levonorgestrel.

The emergency birth control pills containing Levonorgestrel prevent unplanned pregnancy after unprotected sexual intercourse. Compared to other birth control methods, they are as effective as using a male or female condom. 

For example, if 100 couples used the Postinor 2 tablets correctly, around 85 of them will successfully prevent pregnancy (effectiveness rate 85%).

The best time to take Postinor 2 is before ovulation when it is has the greatest chance of working. However, you should take it at any time in your cycle after sex, it if it is the only method you have.

While this does not mean it will always work perfectly, it is better than doing nothing.

And in this article, we hope to explain the issues that may affect how well Postinor 2 works for you.

We recommend you take the pill as soon as possible after sex, but there is a 72-hour window in which it can work.

After this window, Postinor 2 is not reliable as a birth control method.

Within the 72 hours, though, you should know you are better off taking it on the first 24 hours after sex, where it is 95% effective.

This rate drops to 85% from 24-48 hours and further whittles down to 58% if you delay the pill between 48-72 hours.

Now let’s look at common questions you may be wondering about:

side effects of Postinor 2

How Postinor 2 Works

  • #1. What happens if you take postinor 2 while pregnant? 
    • You should not take postinor 2 if you know you are pregnant. If it is taken before you realise you are pregnant, there is no evidence that it can cause any harm to the baby. Studies of women taking postinor 2 did not affect the foetus or the lady if they had taken postinor 2 without realising they were pregnant. However, there is no information on the potential consequences if higher doses (greater than 1.5 mg of Levonorgestrel) are taken. 
  • #2. How should I take postinor 2, so it works fast? 
    • The best way to get the full benefit of the emergency birth control method is to follow the directions on the packet. In that case, you should take the medicine as soon as possible after sex. There are usually two tablets that make up a dose of Postinor 2. You should make sure you have your dose WITHIN 72 hours after sex. Take the first tablet as soon as possible after sex, then the second one 12 hours later. The timing of your cycle also affects how the pill works. Postinor 2 works best when taken before ovulation.
  • #3. How to know if the postinor two worked? 
    • If your next period arrives as scheduled. There are no signs that will tell you if your tablets have worked. Yes, you may have hormone effects like cramps in the tummy, or soreness to the breasts or spotting /bleeding. None of these is a definite sign that you are pregnant. The best way to tell is to do a pregnancy test if your next period is later than 7 days. The earliest urine tests will be positive in 2-3 weeks after sex or when you took your Postinor 2.
  • #4. Can postinor two be used after three days of sex?
    •  You can use it up to 72 hours after sex. However, it is not as effective after the third day as it is within the first 12 or 24 hours after sex. We do not recommend using it more than three days following sex.
  • #5. When to take postinor 2. 
    • You should take Postinor 2 as soon as possible after unprotected sexual intercourse. Since it mainly works by delaying ovulation, the maximum benefit from the medicine is when taken 36 – 40 hours before the day of ovulation.
    • This means if your cycle is regular, every 28 days, your fertile window may be from *days 10 – 15. These are the times in your cycle you are MOST likely to fall pregnant. The Postinor 2 hormone, Levonorgestrel, is most effective taken from *days 9, 10, 11 and 12. They may not work on *day 13 or 14 (ovulation day) or *day 15 (after ovulation). (*Please note these dates are simple estimates for demonstration.)


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Side Effects Of Postinor 2

  • #6. How to take the P2 pill. 
    • You may decide to keep a spare pack of Postinor at home, so it is readily available if you need it. Then straight after sex, take your 1st tablet, followed by a second tablet after 12 hours. If you vomit within two hours after a tablet, please repeat it to make sure it works. Taking it during the first half of your cycle (before you ovulate), is very likely to protect you – (up to 85% effectiveness). If you are very close to ovulation, another pill may be better – Ella; or the Copper coil. The Copper coil is the most effective emergency birth control method. You will need to see a health provider to prescribe and insert the coil.
  • #7. Can postinor 2 flush out sperm? 
    • No, Postinor 2 primarily works by delaying ovulation. Some studies think it may make the mucus in your vagina thicker or change the womb lining so that sperm cannot travel very far in the womb. Or, even if the sperm meets the egg (fertlisation), it may not be able to plant in the womb. However, other studies do not show that postinor 2 does this effectively, so overall, we think the primary way it works is by delaying ovulation. Don’t forget that levonorgestrel delays ovulation by five days. So if you have sex again at this time without protection, you are at a second risk of getting pregnant. So after taking the emergency pill, go back on your regular contraception method or use another emergency contraception again in this instance. 
  • #8. Postinor 2 Side Effects?
    • There is an extensive range of side effects that can develop after you take Postinor 2. 
    • The very common side effects are:
      • Headaches, Nausea, lower Abdominal pain, Bleeding not related to menses, and Fatigue.
    • Common side effects are:
      • Dizziness, Diarrhoea, Vomiting, Delay of menses more than seven days, Irregular Menstruation and Breast tenderness.
    • Rarely there may be:
      • Moderate to severe abdominal pain, Rash, Urticaria, Pruritus, Pelvic pain, Dysmenorrhoea, Face swelling.
  • #9. When is postinor 2 effective? 
    • Postinor 2 is effective when taken as soon as possible after unprotected sexual intercourse and in the part of your cycle before ovulation has happened.
  • #10. Is postinor 2 good for breastfeeding mothers? 
    • Breastfeeding mothers can take Postinor 2. A small amount passes into the breast milk, so the recommendation is for mothers to take the tablet just after a breastfeed.You can then feed your baby with expressed milk until you’ve taken the second tablet.
effects of postinor 2 on the womb

Can Postinor 2 Cause Infertility?

  • #11. Can postinor 2 affect the womb? 
    • Postinor affects the cycle by delaying ovulation. Ovulation happens in the ovary. To a small extent, the Levonorgestrel may also affect fertilisation by preventing sperm from reaching the egg. These effects are not permanent, and postinor 2 does not affect fertility. While the ovulation delay may affect the periods, this effect will also return to normal after some time.
  • #12. Can postinor 2 work during ovulation? 
    • No, Postinor 2 will not work during ovulation. The pills that contain Levonorgestrel work MAINLY before ovulation and will delay the release of the egg till five days after the sperm from that episode of sex have all died. After that, you will ovulate, so get a regular method in place after using postinor 2 the first time. Otherwise, you will need to use another emergency contraception method.
  • #13. Can postinor 2 delay menstruation? 
    • Yes – the hormone in Postinor 2 is known as Levonorgestrel. Ovulation happens when a hormone in the body (luteinizing hormone or LH) gets to a particular level (LH peak). At this stage, your body sends a message instructing the ovary to release a mature egg. When the pill delays the event, the next period can be affected in a couple of ways – either it arrives earlier than usual or later. In some ladies, menstruation comes around the same time of the month as usual.
  • #14. Can postinor 2 cause infertility.
    • No. Taking Postinor can make the menstrual cycle become a little irregular. This can mean menstruation happens earlier or later, but there is no evidence that it affects fertility in the long term. 
  • #15. Will postinor 2 delay period? 
    • Yes, postinor can delay the period in some women. Often the delay is around a week, but less commonly can be even more days or weeks. First, do a pregnancy test if the period is 7 days later than expected. If it’s taking more than a couple of weeks, and a blood pregnancy test is negative, we could consider other possible causes.


  • #16. Can postinor 2 destroy pregnancy? 
    • No, postinor cannot destroy an existing pregnancy – it is not an abortion drug. Studies also do not show any damage or malformation to the baby if the postinor is taken without the woman realising. However, there are no studies on the effect of postinor in pregnancy when taken in large quantity.
  • #17. How many postinor 2 should be taken in a month? 
    • There is no total recommended quantity for postinor 2 tablets to be taken in a month. We advise users that it is only taken occasionally rather than regularly. Even though it is not known to cause harm, it can disrupt the menstrual cycle if you take it very frequently. Ideally, it would be best to not take Postinor more than once in a menstrual cycle, i.e. month. If you need to have it more often, then you should get a regular method of contraception.
  • #18. Can postinor 2 cause bleeding?
    • Certainly, watch this video to learn more – the hormone can cause irregular bleeding unrelated to the menses. It can also affect the menses, making them come earlier or later than usual, complicating the bleeding picture.
  • #19. Why does postinor 2 fail? 
    • There are many reasons Postonor 2 can fail. In our video here, we explain why the emergency contraception pill may fail. In summary:
      • 1. You have not followed the dosing instructions
      • 2. Taking it after ovulation
      • 3. Failing to repeat the dose if you vomit within 2 hours of taking the tablet
      • 4. Taking the wrong dose – especially applies if you are overweight. According to guidelines from the UK’s Faculty of Sexual and Reproductive Health, the standard Postinor 2 dose may not work for you if you weigh over 70 kg (154 lbs) or your BMI is greater than 26. Hence, doctors recommend a higher dose for plus-sized ladies.
      • 5. The pill is not 100% effective; it is typically able to prevent 85 out of 100 pregnancies when taken correctly, so it may simply be a case of the 15% chance it will not work. This is why we advise all women who use an emergency contraception pill to do a pregnancy test once their next period is delayed by more than seven days from its expected date.
  • #20. How much postinor 2 is too much? 
    • Can you take too much Postinor 2? Great question. Some people prefer only to take the emergency birth control pill when they need it rather than a regular method. The usual advice we give is to avoid taking the emergency birth control pill more than once every month when possible.
    • Taking it once a month is not ideal, as the emergency pill should only be used occasionally and not on a frequent or regular basis. Any of the following could be considered as taking the pill ‘too much’:
      • 1. every day,
      • 2. once or twice every week,
      • 3. every month or every 2-3 months, etc
    • I hope you get the picture. Suppose you feel the need to seek emergency contraception so often. In that case, you should consider a long term method like the pill, injection, coil or implant etc. The main problem with taking Postinor too much is the effect on your menstrual cycle. It makes the cycle irregular, so there may be a delay in the period or unpredictable or unscheduled bleeding.
    • The other (also significant problem) is that Postinor 2 is not as effective as long term methods for preventing pregnancy. Taking the emergency contraception pill can also increase the possibility of ectopic pregnancy in women at risk.
Black lady lying on the floor smiling - Does Postinor 2 work during ovulation

Is Postinor 2 effect permanent?

  • #21. How many days postinor 2 last in the body? 
    • After taking Postinor 2, it quickly gets up to maximum levels inside the blood. In many women, this can be within as little as two hours of taking a tablet. Postinor 2 also has a biological half-life of about 26 hours. This means that after reaching its maximum levels, it will take about one day for the levels to drop to half the maximum. You will thus need to take another dose to reach top levels again. So a full dose will last effectively about one day in the body. 
  • #22. Can I take the two pills together instead of 12 hours apart?
    •  In some other countries, you can get the same Levonorgestrel as pills known as Plan B, Take Action, Levonelle etc. The only difference from Postinor 2 is they are single-dose tablets containing 1500mcg (1.5mg) of the drug. Each Postinor 2 tablet contains 750mcg, and the second dose is taken 12 hours after the first. So does this affect how effective they are? According to studies – No. We know that the two tablet course separated by 12 hours prevents 85% of expected pregnancies. If you take the tablets at the same time, it can prevent 84% of pregnancies. It’s important to emphasise that the pills are taken before ovulation and as soon as possible after sexual intercourse (within 72 hours). 

Wrapping Up…

Among emergency contraception methods, Postinor 2 is probably the easiest for you to get hold of. Increasing confidence in its use and clearing up any misconceptions is important. You should also know when it’s most effective – but that should not stop you from using it at any point in your cycle if that is all you can get at the time. Let us know if this post helps, or shoot us any more questions about emergency contraception methods in the comments section below.

Editing by AskAwayHealth Team


All AskAwayHealth articles are written by practising  Medical Practitioners on a wide range of health care conditions to provide evidence-based guidance and to help promote quality health care. The advice in our material is not meant to replace the management of your specific condition by a qualified health care practitioner.
To discuss your condition, please contact a health practitioner or reach us directly through response@askawayhealth.org

Image Credits: Unsplash

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