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How To Know If The Emergency Contraceptive Pill Worked?

An emergency contraceptive pill (ECP) is a vital option for preventing pregnancy after unprotected sex or contraceptive failure. However, many individuals are left wondering how they can be sure that the pill has worked. This blog will provide clarity on the effectiveness of an ECP and how to know if it has worked.

Effectiveness Of An Emergency Contraceptive Pill

An emergency contraceptive pill (ECP) works primarily by stopping or delaying ovulation, and may not work if ovulation has already occurred and the pregnancy has already begun. The effectiveness of an ECP depends on how quickly it is taken after unprotected sex (when no contraception was used) or contraceptive failure (for example, when the condom breaks, slips, or leaks during sex).

The most commonly available ECP in India is the one with a single pill containing Levonorgestrel (LNG). When taken within 24 hours after unprotected sex, this ECP can reduce the risk of an unintended pregnancy by up to 95%. This effectiveness decreases to 85% when taken within 24-48 hours, and further drops to around 58% if taken within 49-72 hours.

effectiveness of emergency contraceptive pill or morning after pill or plan b or ipill or unwanted pill

How To Know If The Emergency Contraceptive Pill Worked: Recognizing The Signs

The primary sign that the ECP has worked is the start of the next period, which should occur at the expected time or within a week of the expected date. If the next period is more than a week late, it is advisable to take a pregnancy test.

Some individuals experience symptoms such as nausea, fatigue, dizziness, headache, or breast tenderness after taking an ECP. It is important to understand that the presence or absence of these symptoms does not indicate whether the pill has been effective in preventing pregnancy.

effectiveness of emergency contraceptive pill or morning after pill or plan b or ipill or unwanted pill and how to know if it worked

Taking A Pregnancy Test

A definitive way to determine if the ECP has worked is to take a pregnancy test. If the next period is more than a week late, or if it is much lighter or shorter than usual, taking a test can provide more clarity.

when to take a pregnancy test and how to take a pregnancy test


The way to know if the emergency contraceptive pill (ECP) has worked is primarily by the timing and normalcy of the next period. While side effects are common, they should not be used as indicators of the pill's effectiveness. If there is a significant delay in your periods or other unusual changes, a pregnancy test can offer clarity.

Remember, an ECP is a safe and effective method to prevent pregnancy after unprotected sex, but it is not a substitute for regular contraceptive methods. For any concerns or further questions about emergency contraception or your reproductive health, consulting a doctor is always recommended. With the right information and responsible use, ECPs can be a reliable backup in your reproductive health toolkit.


This blog, including its text, images, and infographics, are for educational purposes only and not a substitute for professional medical advice. For personalized advice, always consult a doctor.

Further Reading

For more details on this or related topics, refer to the papers listed in references below, the FAQs on the ECP page, or other blogs on the Learn page of our website


  • World Health Organization (WHO). Emergency contraception. 2021.

  • Cleveland Clinic. Morning-After Pill. 2022.

  • Cleveland Clinic. Pregnancy Tests. 2022.

  • Ministry of Health and Family Welfare, Government of India. Guidelines for Administration of Emergency Contraceptive Pills by Health Care Providers. 2008.

  • World Health Organization (WHO). Levonorgestrel 1.5mg tablets, Recommended Patient Information Leaflet. 2021.


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