What you need to know about emergency contraception (EC)
Quick facts
- Take time to choose which form of EC is best for you (see info below). Plan-B (levonorgestrel) is not your only option.
- All forms of EC are most effective when taken as soon as possible and must be used within 5 days of unprotected intercourse to be effective.
- Be sure to take EC properly and follow the post-EC instructions as directed.
- EC does not protect against sexually transmitted infections. Consider getting tested 2-3 weeks after your exposure.
- Don’t take Ella and Plan B at the same time or within 5 days of each other. They can make each other ineffective.
- If you are taking any of the medications on this list, please speak to your medical provider before taking oral EC. See below for an explanation.
Am I at risk for unintended pregnancy?
You should use EC to prevent pregnancy if:
- You didn’t use a condom or other birth control method when you had vaginal sex.
- Your condom broke or slipped off after ejaculation.
- You forgot to take your birth control/missed pills, forgot to change your patch or ring, did not get your depo injection on time and had vaginal sex without a condom.
- You were forced to have unprotected sex.
- If the sex was not consensual, please contact one of our caregivers to learn about the resources available to you, including the VARCC.
What type of EC is right for me?
The selection of an EC agent is mainly driven by individual preference, but there are other considerations as well. The two main types of EC are intrauterine devices (IUD) and oral medications. Each type has advantages and disadvantages. See the comparison chart on the next page for more information that may help you select the best EC option for you.
If you are taking any of the medications on this list, please speak to your medical provider before taking oral EC.
- Intrauterine device (IUD)
- The form of EC that results in the lowest risk of pregnancy is the insertion of an intrauterine device (IUD) within five days of unprotected intercourse. If you wish to use this method, see your gynecologist, or make an appointment at the Decker Student Health Services Center (DSHSC), for a referral to a gynecologist, immediately. You only have 5 days so the appointments must occur quickly. IUDs can be expensive to insert but most insurance plans will cover some or all of the cost, and the IUD can be left in place to provide long-term birth control. The risk of pregnancy if an IUD is put in place within five days after unprotected intercourse is less than 1%.
- Ulipristal (ELLA)
- The most effective oral emergency contraceptive pill is ulipristal (Ella), though it requires a prescription and is more expensive than levonorgestrel (Plan-B). Its effectiveness does not decrease during the five days after unprotected intercourse, but it has no effect when taken after day five. If your Body Mass Index (BMI) is less than or equal to 25 it is likely to be more effective than Plan-B (BMI calculator). On average, the risk of pregnancy drops to 1.8% for women who have taken Ella properly.
- Levonorgestrel (Plan-B)
- Plan-B is available without a prescription and should be taken as soon as possible after intercourse. Plan B is available at the Decker Student Health Services (DSHSC) without an appointment for $10. It works for up to five days after unprotected intercourse, but its effectiveness drops continuously over this time. If taken after day five it has no effect in lowering pregnancy risk. On average, the risk of pregnancy drops to 2.6% when Plan-B is used correctly.
Summary of EC methods and factors to consider for selection
| Factors to consider | Intrauterine device (IUD) | Ulipristal (ELLA) | Levonorgestrel (Plan-B) |
| I want the most effective form of EC | Strongly recommend | Moderately recommend | Recommend |
| I want long-term pregnancy protection | Strongly recommend | - | - |
|
I want the least expensive form of EC |
Recommend | Moderately recommend | Strongly recommend |
| I'm on birth control that involves progesterone | Strongly recommend | Cannot take progesterone birth control for five days | Strongly recommend |
| My BMI is greater than or equal to 25 | Strongly recommend | Moderately recommend | Recommend |
| I have had a malabsorbtive bariatric surgery | Strongly recommend | Recommend | Recommend |
| Low pregnancy risk | Recommend | Strongly recommend | Strongly recommend |
| High pregnancy risk | Strongly recommend | Moderately recommend | Recommend |
| I don't want to take anything that affects my hormones | Strongly recommend | - | - |
| Side effects |
|
|
|
How does EC work?
None of the available methods of emergency contraception work by causing an abortion. ELLA delays ovulation in the pre-ovulatory period and once the surge in luteinizing hormone (LH) releasing the egg has begun. Plan-B only delays ovulation if the LH surge has not started, which may be why it is less effective than ELLA.
There is no theory that fully explains the efficacy of IUDs in emergency contraception. There is strong data showing that they prevent fertilization of the egg when they are used as a continuous contraceptive. It is plausible this is how they work in emergency contraception, but it is also possible that they prevent implantation of the fertilized egg into the uterine lining. Since “pregnancy” is defined by implantation, IUDs do not cause an abortion.
What is my risk of becoming pregnant?
The risk of pregnancy after a single episode of unprotected intercourse depends on many variables. If your risk is low, cost may be a more important factor for you than taking the most effective EC, which tend to be more expensive. The risk of pregnancy is highest if intercourse occurs during the “fertile window,” which is five days before ovulation plus the day you ovulate. Most women ovulate 12-14 days before they expect their next period. It is important to remember that factors like stress or illness can affect your menstrual cycle making your fertile window difficult to predict even if your period is typically regular.
One author assesses pregnancy risk this way:
- Low risk of pregnancy
- Since your last period, a single episode of unprotected intercourse outside of the fertile window
- Failure of a birth control method – for example, a condom broke or slipped; you missed more than one dose of a contraceptive pill in the current pack; you timed your use of depo-provera, vaginal ring, or contraceptive patch incorrectly
- High risk of pregnancy
- You have had more than one episode of unprotected intercourse during your current cycle
- You had unprotected intercourse during your fertile window
- Your periods are irregular
Why does my weight and BMI matter?
Oral emergency contraceptives (both ELLA and Plan-B) become less effective as your weight increases. This effect is most prominent with Plan-B and is less so with ELLA, but does not happen with IUDs. This means ELLA or an IUD may be better choices if your BMI is greater than or equal to 25. However, Plan-B will have some effectiveness and is recommended if neither ELLA nor an IUD are options or are not available within five days. This is the risk of pregnancy, according to the EC method used for BMI categories.
| Method | Pregnancy risk when BMI is 25-29.9 | Pregnancy risk when BMI is greater than or equal to 30 |
| IUD | less than 1% | less than 1% |
| ELLA | 1.1% | 2.6% |
| Plan-B | 2.5% | 5.8% |
Will EC protect me long term?
The only method that can also be used for long-term contraception is an IUD. Some IUDs can give up to 10 years of continuous pregnancy protection, and while they can be expensive to insert, they can be more cost-effective than pills, patches, or rings when they are used for their maximum lifespan.
Can I keep taking my birth control with EC?
If you are taking a birth control with progestreone (pills, patch or ring) when you restart your method depends on which oral EC you choose.
- Plan B: Restart your birth control the day after you take EC. Use a backup method (such as condoms) or do not have vaginal sex until you have used your birth control for at least 7 full days.
- ELLA: Restart your birth control 5 days after you take Ella. Use a backup method (such as condoms) or do not have vaginal sex until after your next menstrual period.
Is EC effective after weight loss surgery or if I have a decreased ability to absorb nutrients?
An oral EC medication may not be absorbed fully under these circumstances. An IUD is your best choice. However, if an IUD is not an option within the five-day window, Plan-B or ELLA taken within the five-day period may have some effectiveness and are still recommended.
What if I vomit after taking an oral EC?
Repeat the dose of oral EC if you vomit:
- Within one hour of taking oral EC for reasons other than having an illness
- Within three hours of taking oral EC due to another illness (viral illness, food poisoning, etc.)
What is my risk for sexually transmitted infections (STI)?
None of the methods used for emergency contraception protect you from STIs. If you need EC, by definition, you have been exposed to potentially infectious material. You should consider getting tested 2-3 weeks after your exposure, or get tested immediately if you develop symptoms of an STI before that time.
Can Plan-B be used more than once in a menstrual cycle?
Plan-B is not intended to be used as birth control. One study was done using Plan-B after each episode of unprotected intercourse when these women had intercourse fewer than six times per month. It resulted in 7.1 pregnancies per 100 women who used this method for a year. Another study showed that when Plan-B is used as the sole method of birth control it resulted in 11 pregnancies per 100 women who used this method for a year.
Are there any drugs that interact with the oral options for EC?
There are many medications that can reduce the blood levels of Ella or Plan-B. These are called “inducers” because they cause an increase in the amount of the enzyme which breaks down oral EC medications. This breakdown leads to reduced blood levels, which may cause the oral EC to be less effective, though there is no proof that they are less effective when this happens. Oral emergency contraceptives can also cause an increase in the blood levels of other medications. In this case, the EC medication is an “inhibitor” of the enzyme which breaks down the other medication. That could lead to side effects or dangerous drug reactions from the drug whose level has been increased.
If you are taking any of the medications on this list of inducers or inhibitors, please speak to your medical provider before taking oral EC to be sure you select the safest and most effective option for you.
