6 Ella Interactions You Should Consider

Ella (ulipristal) is an emergency contraception (“morning after”) pill that helps prevent pregnancy after unprotected sex. You can also take it if your regular birth control method fails (like a condom breaking).

Normally, ella is about 98% effective at preventing pregnancy if taken within 5 days of unprotected sex. However, there are several medications that can make ella less effective, potentially increasing the chance of pregnancy.

Below, we’ll review six ella interactions. But keep in mind this isn’t a complete list of every possible interaction.

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1. Hormonal birth control

While emergency contraception is a form of birth control, ella works differently than hormonal birth control you’d take or use regularly. Hormonal birth control mimics your body’s natural sex hormones (estrogen and progesterone). Ella delays ovulation (the release of an egg) by binding to progesterone receptors (chemical binding sites) in your body.

Birth control that contains a progestin (lab-made progesterone) binds to the same receptors as ella. This interferes with ella’s ability to delay ovulation. At the same time, ella can stop hormonal birth control from binding to progesterone receptors. This means that ella also makes your regular birth control method less effective.

Since hormonal birth control and ella can each make each other less effective, you should wait at least 5 days after taking ella to restart hormonal birth control. This waiting time is the same if you’re going to be starting a new hormonal contraceptive after taking ella. It’s a good idea to use a barrier method of protection, such as condoms, until your next menstrual period.

2. Topiramate

Topiramate (Topamax) is a medication that can help prevent migraines. It can also prevent certain types of seizures. Topiramate may lower the levels of ella in your body. This can make ella less effective and raise the risk of pregnancy.

3. Other seizure medications, such as carbamazepine

Carbamazepine (Tegretol, Equetro), as well as some other seizure medications, can also interact with ella. These seizure medications may lower the level of ella in your body, making it less effective. Other seizure medications that interact with ella include phenytoin (Dilantin) and phenobarbital.

Keep in mind that there aren’t many studies focused on these interactions. But researchers know how the body metabolizes (breaks down) both ella and seizure medications. Given this knowledge, experts warn that an interaction between them is possible. It’s better to be safe and assume ella may be less effective if you also take seizure medications.

4. St. John’s wort

St. John’s wort is an over-the-counter herbal supplement that people take to help ease depression symptoms. St. John’s wort may cause your body to clear ella faster than usual. This could lower levels of ella in the body, possibly making it less effective.

Similar to the interaction with seizure medications, this ella interaction hasn’t been well studied. But based on how the body breaks down ella and St. John’s wort, experts believe an interaction is possible. To be on the safe side, it’s better to presume St. John’s wort may lower ella’s effectiveness.

5. Griseofulvin

Griseofulvin (Gris-PEG) is a medication that treats certain fungal infections. Similar to many of the above medications, it may lower the amount of ella in your body. This could make ella less effective, raising the risk of pregnancy.

Like with other medications discussed earlier, there aren’t many studies available researching this ella interaction. But griseofulvin is known to affect a certain enzyme (protein) in the body that helps break down ella. So an interaction between them is possible.

6. Rifampin

Rifampin (Rifadin) is a medication that treats tuberculosis. Rifampin interacts with many medications, including ella. If taken together, rifampin can speed up how fast your body metabolizes ella. This can lead to lower levels of ella, making it less effective and increasing the chance of pregnancy.

What can you do to manage these ella interactions?

It’s important to talk to your healthcare provider or pharmacist about possible ella interactions before taking it. A medication list is a great tool to have on hand in these situations. It can help your healthcare team suggest the best alternatives for you if needed.

You shouldn’t stop taking any of your medications without talking to your provider. If you take a medication that interacts with ella, you may need to use a different type of emergency contraception, such as Paragard. This is a copper intrauterine device (IUD) that doesn’t interact with other medications.

Why trust our experts?

Written by:

Sarah Morin, RPh

Sarah Morin, RPh, has been a registered pharmacist for over 25 years. She started out as a hospital pharmacist, working at Rhode Island Hospital and then at the University of Connecticut Health Center.

Edited 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.

Reviewed by:

Austin Ulrich, PharmD, BCACP

Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. In his early career, he provided direct patient care in a variety of settings, including hospital and community pharmacies, and in a primary care clinic as a clinical pharmacist.

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