If you’re worried about unintended pregnancy after unprotected sex, you can safely use existing birth control pills as emergency contraception (EC) right away, reproductive health experts say.
In what's known as the Yuzpe method, you take two doses, each containing a combination of 100 micrograms (mcg) ethinyl estradiol (a form of estrogen) and 0.5 milligrams (mg) levonorgestrel (a form of progestin), 12 hours apart, says Michele Bosworth, MD. She coauthored an article about the practice while working for the department of family medicine at the University of Texas Health Science Center in Tyler.
“This is a convenient method for patients to use pills they already have,” she says.
Both doses of pills should be taken as soon as possible, ideally within 72 hours (three days) of unprotected sex, and no later than 120 hours (5 days) after unprotected sex, says Sarah Diemert, NP, a nurse practitioner and the director of medical standards integration for the Planned Parenthood Federation of America.
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Reduce the Risk of Unplanned Pregnancy
“Emergency contraceptive pills work by delaying or preventing ovulation,” Diemert says. “Using emergency contraception correctly after unprotected sex lowers the likelihood of getting pregnant.”
While no contraceptive method can prevent pregnancy with 100 percent certainty, the Yuzpe method of combined oral contraceptives for emergency contraception reduces the risk of pregnancy by roughly 74 percent if started within 72 hours of unprotected intercourse, Diemert says. For extra protection, she recommends using a backup form of birth control for seven days after taking emergency contraception.
The Yuzpe method, which was developed in the 1970s, is less effective and has more side effects than newer forms of emergency contraception, and is typically only recommended if you don’t have access to other methods.
Yuzpe Only Works With Certain Brands of the Pill
Only certain kinds of birth control pills, containing specific doses of both estrogen and progestin, can be used in the Yuzpe method. Look up your brand of birth control pill to see how to use it, if needed, as emergency contraception; with many brands, you need to take multiple pills to get each 100 mcg ethinyl estradiol/0.5 mg levonorgestrel combination dose. Better yet, consult your doctor or pharmacist, or contact a reputable reproductive health clinic like Planned Parenthood for advice.
Using birth control pills this way may cause side effects, including nausea and vomiting. If you throw up within two hours after taking a pill, you should repeat the dose, Diemert says. Other side effects may include breast tenderness, fatigue, irregular bleeding, abdominal pain, headache, and dizziness. “These side effects usually taper off one or two days after taking the pills,” she says.
While research in this area is limited, it is possible that the Yuzpe method may not be as effective in people who are overweight or have obesity, Dr. Bosworth says. Preliminary research on other types of hormonal emergency contraception has found that some forms are less effective in people with a BMI over 30, and Planned Parenthood notes that certain hormonal options see efficacy wane in people over 165 pounds. It’s worth discussing your options, such as having an intrauterine device (IUD) inserted instead of using hormonal emergency contraception, with a doctor or pharmacist if you’re in this category. Emergency contraception will not work if a person is already pregnant, and it won’t harm an existing pregnancy.
If your period arrives within your typical menstrual cycle as expected, you will know you are not pregnant. Be aware that menstrual changes are a side effect of emergency contraception, so later or earlier periods or irregular bleeding are possible.
Still, if your period is delayed, “follow routine practices for taking a pregnancy test, which is any time after it is determined that the menstrual period is late,” Bosworth says. Pregnancy tests detect a hormone called human chorionic gonadotropin (HCG), which is produced only when a fertilized egg attaches to the lining of the uterus, called implantation.
Besides a missed menstrual period, other signs of early pregnancy include nausea, fatigue, sore or enlarged breasts, headaches, and frequent urination. If you’re experiencing these, take a pregnancy test as soon as possible.
If you want to keep using your birth control as ongoing contraception, make sure you continue to use it correctly. Once you have taken extra pills as emergency contraception, talk to your healthcare provider about the following, per Bosworth:
Acquire enough of your needed birth control pills for ongoing contraception.
Determine if you need testing for a sexually transmitted infection.
Talk about whether your current contraception choice is the right one for you. Is it easy to use regularly?
Ensure you are safe if you were involved in nonconsensual sex.
The Yuzpe Method Is One of Several Emergency Options
While there are other forms of emergency contraception, such as pills you can buy over the counter or pills or an IUD you can obtain from a healthcare provider, it’s a better option to use what you already have at home than to not do anything.
“Ultimately, if you can’t get the most effective type of emergency contraception, remember that using whichever method you can get is still better than not using anything at all,” says Diemert. “And timing is really important — you only have up to five days after unprotected sex to use emergency contraception, and sooner is better.”
Overall, consistently using birth control is more effective than relying on emergency contraception, which is always a backup choice and should never be considered the main method of pregnancy prevention.
“Taking contraception on a routine basis is more effective than using emergency contraception to prevent unwanted pregnancies,” says Bosworth. “Women of childbearing age should talk to their doctor regularly about contraception whether they are currently sexually active or not. Proactively anticipating contraceptive needs is key, and the best method is contraception taken on a routine basis.”
The Takeaway
There are several options for emergency contraception, but the Yuzpe method is the only one that may allow you to use the combination estrogen-progestin birth control pills you already have on hand.
While the Yuzpe method is less reliable than other emergency contraception methods — it’s about 74 percent effective if both doses are taken within 72 hours of sex — it’s a good option if your access is limited.
The Yuzpe method involves taking two doses 12 hours apart, each consisting of 100 mcg of ethinyl estradiol (a form of estrogen) and 0.5 mg levonorgestrel (a form of progestin). The number of pills per dose may vary by brand.
If you’re overweight or have obesity, hormonal emergency contraception may be less effective in standard doses. Consult your doctor, a pharmacist, or your local reproductive health clinic for advice.
Kara Smythe, MD, has been working in sexual and reproductive health for over 10 years. Dr. Smythe is a board-certified fellow of the American College of Obstetricians and Gynecologists, and her interests include improving maternal health, ensuring access to contraception, and promoting sexual health.
She graduated magna cum laude from Florida International University with a bachelor's degree in biology and earned her medical degree from St. George’s University in Grenada. She completed her residency in obstetrics and gynecology at the SUNY Downstate Medical Center in Brooklyn, New York. She worked in Maine for six years, where she had the privilege of caring for an underserved population.
Smythe is also passionate about the ways that public health policies shape individual health outcomes. She has a master’s degree in population health from University College London and recently completed a social science research methods master's degree at Cardiff University. She is currently working on her PhD in medical sociology. Her research examines people's experiences of accessing, using, and discontinuing long-acting reversible contraception.
When she’s not working, Smythe enjoys dancing, photography, and spending time with her family and her cat, Finnegan.
Cheryl Alkon is a longtime writer, researcher, and editor. Having experienced health issues for most of her life due to type 1 diabetes, she is fluent in medical terminology and the American healthcare system. She is the author of Balancing Pregnancy With Pre-Existing Diabetes: Healthy Mom, Healthy Baby, a guide to getting and staying pregnant with type 1 or type 2 diabetes.
She graduated from Brandeis University with a bachelor's in English and American studies. She later earned a master’s from Columbia University. She lives in Massachusetts with husband David, son Ethan, and daughter Hannah.
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I took the morning-after pill and got my period a week early. Then I got it again, when it was supposed to happen. What’s going on? Planned Parenthood. April 24, 2020.
