Hi, I'm Dr. Emily Carter, a board-certified OB/GYN with over 15 years of experience in women's health. I understand that unplanned pregnancies can be stressful, and you likely have many questions about emergency contraception, often called the "morning-after pill." Let's discuss how effective they are and what factors might influence their success.

Do morning-after pills work?

The short answer is yes, morning-after pills can be very effective at preventing pregnancy when taken correctly. It's important to remember, though, that they are not 100% effective and work best the sooner you take them after unprotected sex.

Understanding how they work:

There are two main types of morning-after pills available in the United States:

1. **Levonorgestrel pills (Plan B One-Step, Take Action, Aftera, My Way, etc.):** This is the most common type and is available over-the-counter without age restrictions. It contains a synthetic form of the hormone progestin, which works primarily by delaying ovulation. If taken before ovulation, it prevents the release of an egg from the ovary, significantly reducing the chance of fertilization.


2. Ulipristal acetate (ella): This pill is also available by prescription only and contains a different type of medication that also works by delaying ovulation. It may be slightly more effective than levonorgestrel, especially if taken closer to the time of ovulation or if your BMI is over 30.

Effectiveness:

* Levonorgestrel: When taken within 72 hours (3 days) of unprotected sex, levonorgestrel can reduce the risk of pregnancy by up to 89%. This means that out of 100 women who would have gotten pregnant using no contraception, about 11 will still get pregnant despite taking the pill. Its effectiveness does decrease the longer you wait to take it after intercourse.

* Ulipristal acetate: This pill can be taken within 120 hours (5 days) of unprotected sex and is considered slightly more effective than levonorgestrel. Studies show it can reduce the risk of pregnancy by about 85% even when taken closer to the time of ovulation.

Important considerations:

* Timing is key: As mentioned earlier, the sooner you take either type of morning-after pill after unprotected sex, the more effective it will be.
* Weight: Some studies suggest that levonorgestrel may be less effective in women with a BMI over 25, and ulipristal acetate may be a better option. However, both are still recommended for women of all sizes.
* Medications: Certain medications, such as some anticonvulsants and some HIV medications, can interfere with the effectiveness of morning-after pills. It's crucial to talk to your doctor or pharmacist about any medications you are taking to ensure the pill will be effective.
* Repeated use: While morning-after pills are safe to use occasionally, they are not meant to be used as a regular form of contraception. If you are having frequent unprotected sex, consider talking to your doctor about more reliable methods of birth control like the pill, an IUD, or the implant.

What if I experience side effects?

Morning-after pills are generally safe, and most women experience mild side effects, if any. Some common side effects include:

* Nausea
* Vomiting
* Breast tenderness
* Headache
* Fatigue
* Dizziness
* Changes in menstrual bleeding

If you experience severe vomiting within 2 hours of taking either pill, it's important to contact your doctor or return to the pharmacy as you may need to take another dose.

Remember: The morning-after pill is not an abortion pill. It does not terminate an existing pregnancy. If you are already pregnant, the morning-after pill will not harm the pregnancy.

If you have any concerns about emergency contraception or have further questions, please don't hesitate to consult with your doctor or a healthcare professional.

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plan B? comes in a one-pill dose. If taken within 72 hours (3 days) and preferably within 12 hours after a contraceptive accident or unprotected sex, it can prevent pregnancy by doing one of three things: Temporarily stops the release of an egg from the ovary. Prevents fertilization.read more >>