Delay in Period After Taking Emergency Contraceptive: What to Expect?

I took the emergency contraceptive pill (Plan B) and my period is 4 days late! Please help me with this question, doctor..?

I had intercourse with my girlfriend on July 11th between 2 and 3 PM using a condom, but it broke when I pulled out (I'm not sure if there was any ejaculation inside).
Later, my girlfriend checked her app and it indicated that it was a safe period, as her period was due on July 21st.
Therefore, she took emergency contraception (brand: Postinor) around 9 PM that night.
The pharmacy owner also provided her with four supplements (she took two pills along with the emergency contraception and the second dose 12 hours later).
However, by July 24th, her period still hadn't arrived, and she usually has a regular cycle.
This has caused us a lot of concern.
During this time, she did not experience any bleeding, vomiting, or diarrhea.
From July 21st to July 23rd, she kept telling me that she felt pain in her lower abdomen and had breast tenderness, along with some discharge (moist).
Since the symptoms of premenstrual syndrome and early pregnancy are almost identical, it's hard to determine if she is pregnant.
I read online that emergency contraception can have side effects and may cause irregular or delayed periods.
So, I'm wondering if the delay in her period is due to taking the emergency contraception.
I would greatly appreciate any insights from knowledgeable individuals or experienced women.
Thank you very much!

Jain, 10~19 year old female. Ask Date: 2018/07/24

Dr. Huang Jianzhong reply Obstetrics and Gynecology

On July 11, between 2 and 3 PM, I had intercourse with my girlfriend using a condom, but it broke when I pulled out (I’m not sure if there was any ejaculation inside).
Later, my girlfriend checked her app and it indicated that it was her safe period, as her period was due on July 21.
Therefore, around 9 PM that night, she took emergency contraception (brand: 妊止), and the pharmacy owner also provided her with four supplements (two were taken together with the emergency pill, and the second dose was taken 12 hours later).
However, by July 24, her period still hadn’t arrived.
My girlfriend usually has her period on time, so we are quite worried.
During this period, she did not experience any bleeding, vomiting, or diarrhea.
From July 21 to July 23, she kept telling me that she felt pain in her lower abdomen and had breast tenderness, along with some discharge (moist).
Since the symptoms of premenstrual syndrome and early pregnancy are almost identical, it’s hard to determine if she is pregnant.
I read online that emergency contraception can be harmful and may cause irregular or delayed periods.
So, I’m wondering if the emergency contraception could be the reason for her delayed period.
I would greatly appreciate any insights from knowledgeable individuals or experienced women.
Thank you!

Reply Date: 2018/07/24

More Info

When it comes to the use of emergency contraceptive pills (ECPs), such as the one your girlfriend took (妊止), it's important to understand how these medications work and what side effects they may cause, particularly regarding menstrual cycle changes.

Emergency contraceptive pills are designed to prevent pregnancy after unprotected intercourse or contraceptive failure, such as a broken condom. They work primarily by delaying ovulation, which means that if taken before ovulation, they can prevent the egg from being released. However, if ovulation has already occurred, ECPs may not be effective.

In your case, your girlfriend took the emergency contraceptive pill shortly after the incident on July 11. The timing of her menstrual cycle is crucial here. You mentioned that her period was due on July 21, and she took the ECP on the evening of July 11. It is common for ECPs to cause changes in the menstrual cycle, including delays in the onset of menstruation.
The symptoms your girlfriend is experiencing, such as lower abdominal pain and breast tenderness, can be attributed to several factors. These include the hormonal changes induced by the emergency contraceptive, which can mimic premenstrual symptoms or early pregnancy symptoms. The presence of unusual discharge can also be a side effect of hormonal fluctuations.

It is not uncommon for women to experience a delay in their menstrual cycle after taking ECPs. Some women may find that their period arrives earlier or later than expected, and it can be lighter or heavier than usual. The hormonal content of the ECP can disrupt the normal menstrual cycle, leading to these variations.

Given that your girlfriend has a history of regular menstrual cycles, the delay you are observing could indeed be a result of taking the emergency contraceptive. However, if her period does not arrive within a week of the expected date, it is advisable for her to take a pregnancy test to rule out the possibility of pregnancy. Pregnancy tests are most accurate when taken after a missed period.

If the test is negative and her period still does not arrive, it would be wise for her to consult a healthcare provider. They can provide further guidance and check for any underlying issues that may be affecting her menstrual cycle.

In summary, while it is possible that the emergency contraceptive has caused a delay in her period, it is essential to monitor the situation. If her period does not arrive soon, taking a pregnancy test and consulting a healthcare professional would be the best course of action. It’s also important to remember that while ECPs are generally safe, they should not be used as a regular form of contraception due to potential side effects and the impact on the menstrual cycle.

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