Side Effects of Postinor 2 on Menstruation And How to Prevent Them

Just like every other drug used to diagnose, treat or prevent a disease. Postinor 2 can also cause side effects and one among them is its effect on the menstrual cycle. 

In this article, the pharmacist will explain the various side effects of Postinor 2 on menstruation, how it works to bring about these effects, and also the things you can do to either prevent or correct these side effects.

Overview of  Postinor 2

Postinor 2 is a brand name for a synthetic hormone called Levonorgestrel. This hormone works the same way progesterone, a natural hormone that helps facilitate the occurrence of pregnancy works.   

One tablet of Postinor 2 usually contains 0.75 mg of levonorgestrel and you either take 2 tablets at once or take one tablet first and a second tablet 12 hours after the first; all within the first 72 hours after unprotected sex.

When taken correctly and within the right time frame, Postinor 2 can prevent the occurrence of pregnancy by 87% within 72 hours. This success rate is even higher when taken immediately or within the first 24 hours of unprotected sex.

Postinor 2 does not flush out sperm as some people believe it does. Rather, it prevents or delays the release of a viable egg from the ovaries, and also by thickening the mucus in the cervix so that it hampers the free movement of sperm into the uterus and fallopian tube.

In order to better understand the side effects of Postinor 2 on menstruation and how this drug works to bring about these changes to your menstrual cycle. It will help to first of all take a quick look at how menstruation comes about.

The Menstrual Cycle

The menstrual cycle consists of several phases and these phases are summarized below.

The Menstruation Phase (Days 1-5)

The menstruation phase occurs between 1 to 5 days in a 28-day cycle. It marks the beginning of a new cycle.

During this phase, the thick and nutrient-rich inner layer of tissue lining the uterus (endometrium) that was developed and maintained in preparation for pregnancy during the last menstrual cycle, breaks down and is removed through the vagina.

This is often seen as menstrual bleeding which can last an average of 5 days in a 28-day menstrual cycle.

Menstruation only happens if a fertilized egg does not move back to the uterus to attach (implant) to this thickened nutrient-rich tissue prepared for it. This results in a drop in the level of hormones that usually maintain this layer of tissue, hence its breakdown and shedding.

The Follicular Phase (Day 6 – 13)

In this phase, follicle-stimulating hormone (FSH) released by the pituitary gland causes the growth, development, and emergence of one dominant ovarian follicle (egg sac). 

This dominant follicle produces an increased amount of estrogen which causes the walls of the uterus to grow, and thicken in preparation for implantation.

Estrogen also causes the cervical mucus secretions to become thin, clear, and slippery during this phase – creating an optimal pathway for sperm to swim upward toward the uterus and fallopian tube.

One way through which Postinor 2 prevents pregnancy is by reversing this effect of estrogen on cervical mucus. It makes the mucus thick, hence preventing the smooth movement of sperm into the uterus and fallopian tube.

Ovulation (Day 14)

Around the 14th day, there is a spike in the amount of luteinizing hormone (LH). This hormone triggers the rupturing of the mature ovarian follicle and the release of egg into the fallopian tube.

The egg then travels slowly down the adjoining fallopian tube with the hopes of encountering sperm during this day.

Postinor 2 prevents pregnancy by preventing the spike in the amount of luteinizing hormone. Thereby delaying or preventing the release of egg from the ovary. If this stage is blocked, the next phase of the cycle will be altered too.

The Luteal Phase (Days 15 – 28)

During the luteal phase, the now empty ovarian follicle collapses and transforms into a new structure called corpus luteum. This structure acts as a temporary endocrine gland and begins to produce progesterone. 

Progesterone primes and prepares the walls of the uterus for the implantation of a fertilized egg. If implantation occurs and pregnancy is established, the corpus luteum will continue to produce progesterone until the placenta takes over this role.

If there is no pregnancy, the level of estrogen and progesterone will decline significantly by day 28. Since there is no more progesterone to maintain the endometrium, it will break down, shed, and get expelled from the uterus through the vagina. 

This is seen as menstrual bleeding which then marks the beginning of another menstrual cycle.

Postinor 2 does not have any effect on eggs that have already been released, nor on sperm that have already entered into the uterus or fallopian tube. It cannot stop a fertilized egg from implanting neither can it abort or cause miscarriage in an already established pregnancy.

The side effects of Postinor 2 on menstruation 

The major side effects that Postinor 2 have on menstruation include the following:

• Changes in the volume of menstrual flow such as lighter or thicker flow. 
• Changes in the length of menstrual flow (such as flowing for a shorter or longer number of days).
• Alterations in the timing of the menstrual cycle (periods coming sooner or longer than normally expected).
• Irregular periods with unpredictable bleeding.
• Occurrence of breakthrough bleeding.
• Potential influence on menstrual discomfort or cramps.

Postinor 2 is meant to be used only as an emergency contraception to prevent pregnancy in instances of unprotected sex, condom breakage, missed doses, or failure of other contraceptive methods. 

Using it regularly will increase your chances of experiencing these menstrual irregularities and other side effects that are not associated with menstruation.

To reduce your chances of experiencing any of these side effects, it is recommended that you take Postinor 2 only once in a menstrual cycle or once a month.

How Postinor 2 Works To Bring About These Changes In Menstrual Cycle

You’d recall from our discussion on the menstrual cycle, that a normal menstrual cycle involves the interplay of hormones that regulate ovulation as well as the buildup and shedding of the endometrial lining of the uterus.

During a typical cycle, the level of estrogen rises thereby stimulating the growth and thickening of the endometrium during the follicular phase leading up to ovulation.

After ovulation occurs, progesterone levels increase during the luteal phase, which further primes the endometrium to be able to support a fertilized egg.

If no fertilization and implantation occurs, both estrogen and progesterone levels drop at the end of the cycle, triggering menstruation – the shedding of the thickened endometrial lining.

How It Changes Things

Now, when you take levonorgestrel which is the active ingredient in Postinor 2, it will prevent the release of egg from the ovary. Since no egg is released, there won’t be a corpus luteum that will form to produce progesterone needed to maintain the endometrium.

Levonorgestrel is itself a synthetic progestin (progesterone-like drug). So it causes some endometrial growth and priming just like the natural progesterone would do. 

The only issue is that it doesn’t thicken the endometrium to the same viable extent as the natural progesterone would.

Also, since ovulation is suppressed, there is no trigger for a significant dropping in hormone levels (as seen in normal menstrual cycle), and also no corpus luteum breakdown to set off menstruation.

So the uterus is essentially left with a thin, fragile endometrium that has grown haphazardly under fluctuating levonorgestrel effects.

Normally, the endometrium grows and sheds in a uniform or synchronized way each cycle. Without ovulation due to levonorgestrel, the endometrium grows unevenly month to month.

This means that different areas of the uterine lining are potentially in different phases of growth or breakdown at any time.

So, when a particular thickened area of the endometrium loses integrity and breaks down, bleeding occurs from just that area. This is what is seen as spotting or the light unpredictable bleeding occurring in-between periods.

Later, another region may also break down leading to heavier flow. This causes a loss in rhythm in your menstrual cycle, making it difficult to predict or time it.

How Long Do The Side Effects Of Postinor 2 Last?

The side effects of Postinor 2 on menstruation are often temporary and usually stop about 1 to 3 months after discontinuing the medication. 

Menstrual irregularities such as lighter, heavier, or prolonged periods as well as intermittent spotting and cessation of period typically last for as long as Postinor 2 is being taken and sometimes up to a few months after stopping. 

That’s because as long as you are still taking the drug, it will keep on preventing ovulation which will as a result cause the alteration in associated hormonal levels (estrogen & progesterone) and every other process peculiar to an undisturbed menstrual cycle.

However, if you discontinue the drug, your menstrual cycle is likely to return to normal between 1 to 3 months (or cycles) after a balance has been returned to your hormones and the natural processes of menstruation.

If these changes do not return to normal 3 months after discontinuing the pill, you should see a gynecologist for an expert solution.

Other Commonly Asked Questions About the Side Effects of Postinor 2

What Are the Disadvantages of Postinor 2?

While Postinor 2 is effective as emergency contraception, It also has some drawbacks.

This includes causing side effects such as headache, nausea, vomiting, breast pain, acne, dizziness, temporary menstrual irregularities like unexpected bleeding or spotting, heavier periods, and delayed or missed periods. 

These effects are often temporary for most women, but can persist for months after stopping for some. Postinor 2 can fail to prevent pregnancy if taken too late (i.e beyond 72 hours after unprotected sex).

It also does not protect against sexually transmitted infections if exposure occurs.

Does Postinor 2 Delay Period?

Yes, taking Postinor 2 can delay your next expected period by up to one week, sometimes longer.

It does this by suppressing the release of egg from the ovary and also by altering hormonal patterns that control the menstrual cycle.

Cycles typically revert back to normal within 1-3 months after stopping depending on how quickly your hormones rebalance.

How Long Does Postinor 2 Delay Ovulation?

When taken correctly within 72 hours of unprotected sex, Postinor 2 can delay ovulation by at least 5-7 days, sometimes longer.

This gives enough time for any sperm present in the vagina to die off since it can only survive for about 5 days. 

Can Postinor 2 Cause Infertility?

No, taking Postinor 2 will not reduce your fertility or cause any infertility issues in the future. There is no scientific evidence of such an effect.

What the synthetic hormone in Postinor 2 does is to temporarily pause ovulation and alter your menstrual cycle. 

These actions are fully reversible and as such, your hormonal system and ovaries should return to normal functioning within a few natural cycles after you stop the pill.

Does Postinor 2 destroy the womb?

No, Postinor 2 does not destroy or harm the womb (uterus) in any way. As earlier stated, the hormone in Postinor 2 works by temporarily stopping ovulation, thickening the mucus in the cervix, and altering hormonal signals to and within the uterus. 

It does not damage the physical structure or lining of the uterus itself. The changes to your menstrual cycle and fertility from taking Postinor 2 are fully reversible and everything should go back to normal within 1-3 months after you’ve stopped taking it.

Does Postinor 2 Cause Bleeding?

Yes, one of the common temporary side effects of taking Postinor 2 is abnormal uterine bleeding.

This is because it alters the once properly coordinated hormonal signals that allow the uterine lining to build up and shed uniformly. 

Thereby, making it to now thicken and shed unevenly. This can cause unexpected spotting between periods, heavier/longer periods, or even a lack of periods.

For most women this bleeding is temporary, but very heavy or persistent bleeding warrants seeing your provider to rule out other gynecologic issues. 

Final Thoughts

Postinor 2 causes side effects the same way other medications do. However, these changes in the menstrual cycle are often temporary and once the drug is stopped and balance is restored to hormone levels in the body, the effects usually resolve. If it doesn’t, you’ll need to go for a checkup by a gynecologist.

References

• Gainer E, Kenfack B, Mboudou E, Doh AS, Bouyer J. Menstrual bleeding patterns following levonorgestrel emergency contraception. Contraception. 2006 Aug;74(2):118-24. doi: 10.1016/j.contraception.2006.02.009. Epub 2006 Apr 27. PMID: 16860049; PMCID: PMC1934349.
• Okewole IA, Arowojolu AO, Odusoga OL, Oloyede OA, Adeleye OA, Salu J, Dada OA. Effect of single administration of levonorgestrel on the menstrual cycle. Contraception. 2007 May;75(5):372-7. doi: 10.1016/j.contraception.2007.01.019. Epub 2007 Mar 29. PMID: 17434019.
• Arowojolu AO, Okewole IA. Vaginal bleeding following the use of a single dose of 1.5mg levonorgestrel (LNG) for emergency contraception. West Afr J Med. 2004;23(3):191–3.
• Westley E, Glasier A. Emergency contraception: dispelling the myths and misperceptions. Bull World Health Organ. 2010 Apr;88(4):243-4. doi: 10.2471/BLT.10.077446. PMID: 20431781; PMCID: PMC2855611.