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Emergency Contraceptive Pills: How They Work, Safety and Side Effects

An overview of how the emergency contraceptive pill works, safety and common side effects

Video transcript

Hello and welcome to “VideoScript”, presented by

Today in the second of three presentations, we continue reviewing the emergency contraceptives Plan B One Step, Next Choice One Dose, and Next Choice.

We will review how emergency contraception works and issues related to safety and side effects.

Please review all 3 videos for the most complete information.

So how do these emergency contraceptives work? Levonorgestrel, the medication found in these medications, works by preventing or delaying the release of the egg from the ovary.

Emergency contraceptives may also alter the cervical mucous or reduce the ability of the sperm to bind to an egg.

Studies have shown levonorgestrel emergency contraception may have a lower effect in obese women, and a physician may determine that another type of emergency contraception, such as Ella or the copper IUD, may be a more effective option. Be sure to contact your physician if you have a concern about this.

Emergency contraceptive pills are very safe to use and side effects are usually short-term and mild.

Nausea has been reported in about 1 out of every 5 women using levonorgestrel emergency contraception. Vomiting may also occur in about 1 out of every 17 women. If vomiting should occur within 3 hours of taking an emergency contraceptive, women should contact their health care provider as a repeat dose may be needed.

Other short-term side effects include irregular bleeding or spotting, headache, breast tenderness or stomach pain.

Studies have shown that levonorgestrel emergency contraception use does not increase risk to the developing fetus in women who may not yet know that they are pregnant. However, the emergency contraceptive pill should not be used by a woman if she knows that she is pregnant.

Women who cannot use combined birth control pills because of medical conditions such as migraines, heart or liver conditions, or breastfeeding can still safely use emergency contraception, as it is just a one –time dose. However, it is best to check with your doctor first.

Using the emergency contraceptive pill on a regular basis for long-term birth control is not a good idea: it can be costly and inconvenient, is not as effective as other options for birth control, it may expose the woman to higher total levels of hormones, and it may lead to continued side effects, such as irregular periods.

However, if unprotected sex should reoccur, even within the same cycle, it is safe to use the levonorgestrel emergency contraceptive pill again if needed. A health care provider should be contacted as soon as possible so that a regular form of birth control can be initiated for ongoing use.

Thank you for joining us at for a brief review of emergency contraceptives. Please refer to our patient and professional information, drug interaction checker, and additional tools on

Patients with a concern about the use of Emergency Contraception should consult with their health care provider.

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Ovulation Animation

This animation shows the process of ovulation (the release a single egg cell from an ovary). Ovulation occurs though a sequence of hormonal responses. Located deep within the brain, the pituitary gland releases the hormones FSH and LH, which travel through the blood stream to the ovaries. These hormones signal the development and release a single egg cell from one of the ovaries. The sweeping motion of the fimbriae draws the egg cell through a very small space in the open body cavity into the uterine, or fallopian, tube. The egg cell will either be fertilized by sperm or will dissolve if fertilization does not take place.


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Intracytoplasmic sperm injection

This animation shows the process of Intracytoplasmic sperm injection (ICSI), a procedure used to fertilize an egg cell outside of the body.

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