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How Long Does It Take the Morning After Pill to Work?

Sunshine is streaming through the window, but anxiety fills your mind.  The simple act of getting out of bed feels daunting.  Maybe the contraceptive method you tried was unsuccessful, or the sex was spontaneous and birth control wasn’t used.  But you realize that pregnancy is one possible outcome, and this feels frightening.  You may be thinking of taking the morning after pill or Plan B, but how long does it take for it to work?

If you’re wondering about your risk of an unexpected pregnancy, our expert staff at Avenue Women’s Center is here for you!  Since 1981, we’ve been providing free services for those concerned about an unexpected pregnancy.  We offer medical-grade pregnancy tests, 99.5% accurate just ten days after possible conception.  When you visit one of our limited medical clinics, you’ll have an opportunity to meet with a caring pregnancy consultant. We’ll provide information on your options and resources, supporting you as you process your next steps forward.

Schedule an appointment at one of our six locations in DuPage County, IL today!

The Morning After Pill:  What is it, and How Does it Work?

The morning after pill is emergency birth control which can be taken by a woman after sex to help prevent pregnancy if the sex was unprotected or if a birth control method was unsuccessful.  It’s made with levonorgestrel (as with Plan B One-Step, Aftera, and others) or ulipristal acetate (ella).  The morning after pill is different from everyday oral contraceptives and is intended only as an occasional backup option.  It’s also distinct from the abortion pill.  You may be wondering, “How?”  According to the Mayo Clinic, the abortion pill ends a pregnancy in which an egg has already been fertilized and fixed to the wall of the uterus.  The morning after pill, on the other hand, is designed to prevent or delay ovulation (the release of an egg) in the first place.

What About the Timing?

Different forms of the morning after pill have different timeframes during which they remain effective.  Depending on the pill type, they may be recommended for use as soon as possible after sex, up until three, four, or five days later.  This is not to be taken as medical advice.  If you choose to explore the option of emergency contraceptives, consider discussing this with your doctor.  A physician may provide a recommendation based on your unique situation and discuss how/when to take the pill effectively.  Some morning after pills can be purchased over the counter, while others require a prescription.

Effectiveness and Other Considerations

Because the function of the morning after pill is to prevent ovulation, it will not be effective in preventing pregnancy if ovulation has already taken place.  Although the morning after pill has a generally high rate of effectiveness when used directly as intended, no form of emergency contraception is guaranteed to prevent pregnancy.  Various factors contribute to effectiveness. A medical professional may provide additional information about this. The morning after pill also does not prevent the spread of sexually transmitted infections.

Support is Available!

If you’re wondering how the morning after pill works, you may be concerned about a possible pregnancy.  Perhaps you’ve noticed some signs and symptoms of pregnancy or even received a positive pregnancy result.  An unexpected pregnancy or pregnancy scare can feel overwhelming, and so can the mere possibility of this.   But you don’t have to face these circumstances alone.  There are free resources available to shed light on your unique situation and to help you navigate a path forward.

At Avenue Women’s Center, we’re committed to equipping you with accurate information and resources so you feel empowered to make choices with confidence.  If a pregnancy is confirmed, we’ve got your back.  Additional services including (but not restricted to) limited medical ultrasounds are offered free of charge.

Check out our services!  We want to come alongside you in this time of uncertainty.



Reviewed by Patricia Kuenzi, APN-CNP, MSN, ANP, PNP.

The information provided here is general in nature.  It is not a substitute for a consultation with a medical professional. Before any medical procedure, it is imperative that you discuss your personal medical history, risks, and concerns with your doctor. If you have questions during or after a procedure, your doctor should be immediately contacted. Avenue Women’s Center is not an emergency center.  If you are experiencing severe symptoms, such as bleeding and/or pain, seek immediate medical attention.  Contact your physician, go to an emergency room, or call 911.