Is the Yuzpe Method a Safe and Effective Form of Emergency Contraception?

The terms “emergency contraception” and “morning-after pill” are often used interchangeably. Emergency contraception is a term used to describe methods to prevent pregnancy after having sex. The morning-after pill is a common name for Plan B One-Step (levonorgestrel). 

Plan B is one of the most common forms of emergency contraception, but it’s not the only one. Other options include the Yuzpe method, which involves using regular birth control pills as emergency contraception. 

Here, we’ll cover everything you need to know about the Yuzpe method — how it works, how to use it, and how safe and effective it is.

What is the Yuzpe method?

The Yuzpe method involves the use of birth control pills as a form of emergency contraception. Only specific birth control pills — called combined oral contraceptives (COCs) — can be used in this method. COCs contain both estrogen and progestin (lab-made version of the sex hormone progesterone). 

The Yuzpe method is just one of the emergency contraception methods available in the U.S. Other options include:

• Levonorgestrel products. This oral medication is available over-the-counter and contains levonorgestrel (a progestin) only. There are several brand and generic names, including Plan B One-Step, Take Action, and AfterPill. It should be taken within 3 days of having unprotected sex.

• Ella (ulipristal). This prescription-only medication is taken by mouth and can be used up to 5 days after having unprotected sex.

• Paragard intrauterine device (IUD). Paragard is a small device placed in your uterus. It contains copper and is hormone-free. 

Both ella and levonorgestrel products are FDA-approved for emergency contraception. Paragard and the Yuzpe method are used off-label as emergency contraception. This means they are not FDA-approved for this reason.

How do I use the Yuzpe method?

The Yuzpe method was first tested in the 1970s. It involves taking two doses of COCs. The two doses should be taken 12 hours apart. Each dose should contain a minimum amount of estrogen and progestin in specific forms:

• Estrogen: at least 0.1 mg of ethinyl estradiol 

• Progestin: at least 0.5 mg of levonorgestrel or 1 mg norgestrel

You’ll need to take more than one pill in each dose. For example, if your birth control pills contain 0.02 mg ethinyl estradiol and 0.1 mg of levonorgestrel (like Aviane), you’ll need to take five tablets per dose, and then repeat that dose 12 hours later. Five tablets gives you 0.1mg of ethinyl estradiol and 0.5 mg of levonorgestrel per dose.

But, it’s possible that you’ll need to take more estrogen and progestin than the minimum amounts listed above. For example, if your pills contain 0.03 mg ethinyl estradiol and 0.3 mg norgestrel (like Cryselle), you'll take four tablets per dose. This will give you 0.12 mg of ethinyl estradiol and 0.6 mg of norgestrel per dose.

Not all birth control pills contain these certain estrogens or progestins. If you’re wondering whether your birth control pills can be used as emergency contraception, talk to your pharmacist. They can check your specific birth control product and let you know if it can be used as emergency contraception. They can also tell you the correct way to take it.

How does the Yuzpe method work?

Researchers don’t know exactly how the Yuzpe method prevents pregnancy. It’s likely that a few different factors come into play. Possible theories include:

• Prevents ovulation (the release of an egg). For pregnancy to occur, your ovaries have to release at least one egg during the ovulation phase of your menstrual cycle. 

• Disrupts the luteal phase. Your menstrual cycle is made up of phases. The luteal phase is the time between ovulation and your period starting. This is when your uterus prepares for a potential pregnancy. If this phase is disrupted, pregnancy can be prevented.

• Changes in the endometrium. The endometrium is the tissue that lines the uterus. It changes throughout your menstrual cycle in response to hormones like estrogen. It has to thicken for pregnancy to happen. Some changes to the endometrium can affect your ability to get pregnant.

• Lowered hormone levels. The Yuzpe method may lower the level of certain hormones needed for pregnancy to occur. These include estrogen, luteinizing hormone (LH), and follicle stimulating hormone (FSH).

• Changes to the cervical mucus. In order for a sperm to enter an egg (conception), sperm need protection while traveling along the female reproductive tract. Cervical mucus is the fluid that provides this protection. The amount and quality of your cervical mucus is important, and any changes can affect your ability to get pregnant.

• Prevents a sperm from fertilizing an egg. It’s possible that the Yuzpe method prevents the fertilization process itself. If a sperm cannot fertilize an egg, pregnancy cannot occur.

It’s also possible that the time when you use the Yuzpe method during your menstrual cycle matters. The day before or the day of ovulation might be too late. If the Yuzpe method prevents pregnancy by preventing ovulation, then it might not prevent pregnancy if you’re already ovulating.

Is the Yuzpe method effective?

The Yuzpe method can be a convenient method of emergency contraception, especially if you’re able to use the birth control pills you already have. But the Yuzpe method is not the most effective form of emergency contraception. This means other forms of emergency contraception are better at preventing pregnancy:

• Paragard: 99.9%

• ella (ulipristal): 98%

• Levonorgestrel products: 87%

• Yuzpe method: 74%

The Yuzpe method is the least effective form of emergency contraception, but it still significantly lowers the chance of pregnancy compared to not using emergency contraception at all. It’s most effective in the 72 hours (3 days) after having sex, but can be used up to 120 hours (5 days) after sex.

Is the Yuzpe method safe?

Yes, the Yuzpe method is safe for most people. 

But, if you’re over the age of 35 and you smoke, COCs aren’t the best option for you. This is because estrogen can raise your risk for blood clots.

A progestin-only pill, like Plan B One-Step or Paragard might be a better option. This also applies to people with certain health conditions. These include people with a history of blood clots, stroke, or heart attack.

If you’re not sure whether the Yuzpe method is safe for you, talk to your healthcare provider. They can let you know if you’re better off trying another emergency contraception option.

Does the Yuzpe method have any side effects?

It can.

Like all medications, birth control pills may have side effects. The most common side effects of the Yuzpe method are nausea and vomiting. Vaginal bleeding and tiredness may occur, as well.

These side effects usually go away on their own. If you have any bothersome side effects that don’t seem to improve even after you’ve finished taking your doses, talk to your healthcare provider.

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Written by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

Reviewed by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

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