If you’re sexually active, there’s always a chance that you could get pregnant, even if you’re using protection. Perhaps you’re thinking about taking Plan B to avoid an unplanned pregnancy. However, Plan B isn’t foolproof and it’s not without its risks. It’s important to be aware of how Plan B could affect your body and what to do if it fails.

How Does Plan B Work?

Plan B is a form of emergency contraception (also known as emergency birth control) that aims to lower the risk of pregnancy by preventing or delaying ovulation[1]. It’s important to know that Plan B (and all other forms of emergency contraception) should not be used in place of regular birth control[1]. It should also be noted that Plan B tends to be less effective for women who weigh 165 pounds or more[2]

Is Plan B an Abortion Pill? Can Plan B Cause Miscarriage?

While they seem similar, Plan B and the abortion pill aren’t considered the same. The difference is that the goal of Plan B is to delay ovulation, while the abortion pill ends a pregnancy that has already begun to develop[1]


That being said, in rare cases, Plan B can prevent a fertilized egg from implanting into the uterus by cutting off nourishment to the embryo[3].

What are the Side Effects of Plan B?

It’s important to be aware of the potential side effects of Plan B so you can protect your health! Common side effects of Plan B include[1]:


  • Breast tenderness
  • Dizziness
  • Headaches
  • Fatigue
  • Cramps or abdominal pain 
  • Nausea or vomiting
  • Irregular periods
  • Allergic reaction to levonorgestrel (a hormone found in Plan B)

Can Plan B Cause Irregular Periods?

As mentioned above, Plan B can cause irregular periods, which can be alarming if you’re concerned about being pregnant. You may experience a delayed period (up to a week), a heavier flow during your next period, or bleeding between periods[1].


If you experience spotting or bleeding for more than a week or severe abdominal pain three to five weeks after taking Plan B, contact your healthcare provider immediately. These symptoms can indicate that you became pregnant, but a miscarriage or ectopic pregnancy occurred[1].

What to Do if Plan B Fails

If your period is delayed for more than three to four weeks after taking Plan B[1], the next step is to determine whether or not you’re pregnant. Right now, the idea of taking a pregnancy test may feel terrifying. You don’t have to take this step alone! Consider scheduling a free pregnancy test and free ultrasound at Care Net Owensboro! 


If your results come back positive, don’t panic. Our compassionate staff 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 confidently take your next steps!


Don’t wait to get the care you deserve! Call or text us at (270) 685-5077 or schedule your appointment online today!



  1. 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#  
  2. Cleland, K., Raymond, E. G., Westley, E., & Trussell, J. (2014, December). Emergency contraception review: Evidence-based recommendations for clinicians. Clinical Obstetrics and Gynecology. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4216625/  
  3. Embryocidal Potential of Modern Contraceptives. AAPLOG. (2020, January 15). Retrieved from https://aaplog.org/wp-content/uploads/2020/01/FINAL-CO-7-Embryocidal-Potential-of-Modern-Contraception-1.20.20.pdf