In short

  • Levonelle contains levonorgestrel, a synthetic version of the progesterone hormone.
  • Levonelle primarily works by preventing the release of an egg (ovulation).
  • However, it also increases the thickness of the mucus around the cervix.

Levonelle contains levonorgestrel, a synthetic version of the progesterone hormone. Levonelle primarily works by preventing the release of an egg (ovulation). However, it also increases the thickness of the mucus around the cervix. This can help by creating a barrier, making it difficult for sperm to pass through. 

How effective is Levonelle?

Levonelle is considered to be 95% effective if taken 12 hours after unprotected sex. After 48 hours, the effectiveness of Levonelle is reduced to 58%. Other morning after pills, such as ellaOne can be effective up to 5 days after intercourse.

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Sources

References

1 source was selected to match the subject of this article. Link destinations were checked twice when added. This does not mean every statement has been individually source-mapped or clinically approved.

  1. Emergency contraception

    NHS · HTML · NHS contraception guidance · Link destination checked 5 September 2026

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Who wrote this

Written and reviewed by our team

Authored by

Ian Coakley, Content Writer

Content Writer

Ian is Simple Online Pharmacy’s Content Writer; he joined the team in 2021. He has had a varied career path, starting as a science communicator and freelance editor and writer. While Ian has been published in some independent outfits, Simple Online Pharmacy marks his first foray into writing for a corporate entity.

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Medically reviewed by

Karim Nassar, Co-Founder, Pharmacist & Author

Karim Nassar

Co-Founder, Pharmacist & Author

Karim is a registered pharmacist with the General Pharmaceutical Council (GPhC) and was a founding member of Simple Online Healthcare in 2015. With a Master of Pharmacy degree from Strathclyde University, Karim brings a strong foundation in pharmaceutical care and a passion for leveraging digital solutions to improve patient access to healthcare.

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