Plan B: How it Works, Side Effects, and More

Nov 4, 2024 | Abortion

Even if you’re using protection, there’s always a chance that you could get pregnant. Perhaps you’ve turned to Plan B to avoid an unplanned pregnancy. But, what happens if Plan B fails? It’s crucial to understand your pregnancy options so you can plan your next steps!

Today, we’re discussing Plan B—including how it works, the risks and side effects, and what to do if you still get pregnant after taking it. Keep reading to learn more!

 

How Does Plan B Work?

Plan B is a form of emergency contraception that lowers the risk of pregnancy by preventing or delaying ovulation. It’s often used when birth control fails or in cases of sexual assault.

However, Plan B doesn’t always prevent ovulation,[1,2,3] but may also work by disrupting the hormonal environment and interfering with the embryo’s attachment to the uterus, resulting in its death.[4,5]

It’s important to know that Plan B and all other forms of emergency contraception should only be used as backups, not as primary methods of birth control.[6]

 

Is Plan B an Abortion Pill?

While they seem similar, Plan B and the abortion pill are not the same things. The difference is that Plan B aims to keep you from getting pregnant in the first place and may disrupt a newly formed embryo from continuing to grow[7], but the abortion pill is designed to end a pregnancy every single time it is used.

If you have been sexually active in weeks prior to taking Plan B you may want to take a pregnancy test or even receive an ultrasound just to be certain that you’re not pregnant from a previous sexual encounter.

 

Can Plan B Cause Miscarriage?

A miscarriage is an unintended loss of a pregnancy before the 20th week of pregnancy. While the goal of Plan B is to prevent pregnancy altogether, if an embryo has already formed when Plan B is taken, it may interfere with the embryo’s ability to attach to the uterus, resulting in its death.[8]

Additionally, the Mayo Clinic warns that taking Plan B while pregnant can harm the fetus.[9] If you suspect you might be pregnant because have been sexually active in weeks prior to taking Plan B, you want to be certain you’re not pregnant. You can confirm with a pregnancy test.

 

How Effective is Plan B? When Can I Take Plan B?

Plan B is most effective when taken as soon as possible after having unprotected sex. It is reported to reduce the risk of pregnancy for up to 72 hours, but is not always effective.[10]

 

Does Plan B Have Side Effects?

Common side effects of Plan B include[11]:

  • Dizziness
  • Headache
  • Cramps or abdominal pain
  • Nausea or vomiting
  • Breast tenderness
  • Delayed period, irregular bleeding, and/or heavier bleeding during your next period[12]

These side effects should be mild and only last a few days. However, if you experience bleeding or spotting for longer than a week or have significant lower abdominal pain after taking Plan B, contact your healthcare provider immediately, to be evaluated for a miscarriage or an ectopic pregnancy.[13]

 

What to Do if Plan B Fails

If you’ve taken Plan B and missed your period, it could mean that you’re pregnant.[14] The next step is to find out for sure. Consider scheduling a free pregnancy test consultation at Bridgehaven Pregnancy Support Center!

If your results come back positive, don’t panic. Our compassionate team is here to help you explore all of your pregnancy options so that you can make an informed and empowered decision! We will do everything we can to equip you to take your next steps with confidence!

Give us a call at (319) 220-3077 or make an appointment online today. All services are confidential and free of charge!

Request an Appointment

Please be aware that Bridgehaven Pregnancy Support Center does not provide or refer for abortion services.

 

Sources

  1. Hapangama D, Glasier AF, Baird DT. “The effects of peri-ovulatory administration of levonorgestrel on the menstrual cycle.” Contraception. 2001 Mar;63(3):123-9. DOI:10.1016/s0010-7824(01)00186-x Available at: https://www.contraceptionjournal.org/article/S0010-7824(01)00186-X/fulltext
  2. Croxatto, HB, Brache V, Pavez M, Cochon L, Forcelledo ML, Alverez F, Massai R, Faundes A, and Salvatierra AM, 2004. “Pituitary-ovarian Function Following a Standard Levonorgestrel in Emergency Contraception Dose or a Single 0.75 mg Dose Given on the Days Preceding Ovulation.” Contraception. 2004 Dec;70(6):442-50. DOI:10.1016/j.contraception.2004.05.007 Available at: https://www.contraceptionjournal.org/article/S0010-7824(04)00156-8/fulltext
  3. Marions L, Cekan SZ, Bygdeman M Gemzell-Danielsson K. “Effect of emergency contraception with levonorgestrel or mifepristone on ovarian function.” Contraception. 2004 May;69(5):373-7. DOI:10.1016/j.contraception.2003.11.018 Available at: https://www.contraceptionjournal.org/article/S0010-7824(03)00349-4/fulltext
  4. Meng CX, Marions L, Bystron B, GemzellDanielsson KG. “Effects of oral and vaginal administration of levonorgestrel emergency contraception on markers of endometrial receptivity.” Hum Reprod. 2010 Apr;25(4):874- 83. DOI: 10.1093/humrep/deq007. Epub 2010 Feb 6. Free full text: Evidence-Based Guidelines for Pro-Life Practice 32 https://academic.oup.com/humrep/article/25/4/874/699368
  5. Achache H, Revel A. “Endometrial receptivity markers, the journey to successful embryo implantation.” Hum Reprod Update. 2006 Nov-Dec;12(6):731- 46. Epub 2006 Sep 18. DOI:10.1093/humupd/dml004 Free full text: https://academic.oup.com/humupd/article/12/6/731/624054
  6. Mayo Foundation for Medical Education and Research. (2022, June 3). Morning-after pill. Mayo Clinic. Retrieved from https://www.mayoclinic.org/tests-procedures/morning-after-pill/about/pac-20394730#
  7. Kahlenborn, C., Peck, R., & Severs, W. B. (2015). Mechanism of action of Levonorgestrel emergency contraception. The Linacre Quarterly, 82(1), 18-33. https://doi.org/10.1179/2050854914y.0000000026
  8. See source #4.
  9. Mayo Foundation for Medical Education and Research. (2022, June 3). Morning-after pill. Mayo Clinic. https://www.mayoclinic.org/tests-procedures/morning-after-pill/about/pac-20394730#
  10. See source #1.
  11. Levonorgestrel (Oral Route) Side Effects. Mayo Clinic. (2024, September 1). https://www.mayoclinic.org/drugs-supplements/levonorgestrel-oral-route/side-effects/drg-20074413
  12. See source #6.
  13. See source #6.
  14. See source #6.