If you’re sexually active, there’s always a chance you could get pregnant, even when using protection. Perhaps you’re considering Plan B to avoid an unexpected pregnancy. It seems like a simple fix, but it isn’t without its risks. Before taking Plan B, it’s crucial to understand how it can affect your body and what to do if it fails.

Today, we’re sharing about Plan B — how it works, the potential risks and side effects, and what to do if you still get pregnant after taking it.

How Does Plan B Work?
Plan B is intended to be taken within 72 hours after unprotected sex. It contains a high dose of progesterone (levonorgestrel) that is found in many kinds of birth control pills. Plan B can prevent ovulation. It also affects the lining of your fallopian tubes so sperm cannot reach a released egg. It can irritate the lining of the uterus and make it harder for an embryo to implant into the uterus. Plan B (and any other form of emergency contraception) should not be used as a replacement for 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? Does Plan B Cause Miscarriage?
They may seem similar, but Plan B and the abortion pill are not considered the same things. The difference is that Plan B aims to delay ovulation or prevent fertilization (as mentioned above), while the abortion pill ends a pregnancy that has already started[1].

That being said, Plan B can prevent a fertilized egg from implanting into the uterus[3]. The embryo never gets the chance to develop into a viable pregnancy and is eventually expelled from the body.

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. Plan B has been known to cause[1]:

• Nausea and vomiting
• Irregular periods
• Cramping and abdominal pain
• Fatigue
• Headache
• Dizziness
• Breast tenderness

Can Plan B Cause Irregular Periods?
As mentioned above, Plan B can cause irregular periods, which can be stressful to deal with if you’re concerned about an unexpected pregnancy. After taking Plan B, your period could be delayed up to a week. You may also experience bleeding between periods or heavier bleeding during your next period[1].

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

What if Plan B Fails?
If your period is delayed for more than three to four weeks after taking Plan B, it may be a sign that it failed[1]. Your next step is to determine whether or not you’re pregnant. Consider requesting a free pregnancy test and ultrasound at Essential Pregnancy Services (EPS).

If your pregnancy test comes back positive, don’t panic. Our professional counselors are here to help you explore all of your pregnancy options so that you can make an informed and empowered decision. We will equip you to take your next steps with confidence!

Don’t wait to get the care you deserve! Request your appointment online today! To speak with a nurse now, call or text our confidential helpline.
1. Mayo Foundation for Medical Education and Research. (2022, June 3). Morning-after pill. Mayo Clinic. Retrieved from
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
Embryocidal Potential of Modern Contraceptives. AAPLOG. (2020, January 15). Retrieved from