Contraceptive Pearl: Ulipristal Acetate Myths

Written by Veronica Flake, MD

Ulipristal Acetate (ella, UPA) is an effective emergency contraception (EC) method, given as a one-time, 30-mg dose, which can be used for up to 120 hours after unprotected sexual intercourse to prevent pregnancy. UPA is a selective progesterone receptor modulator with antagonistic and partial agonistic effects that prevents or delays ovulation after the LH surge has begun. Its half-life of 32 hours renders it more effective than levonorgestrel emergency contraception (LNG EC), as the latter is no longer effective at that point. Regarding efficacy, clinical trials have noted pregnancy rates following the use of UPA within 120 hours of sexual intercourse ranged from 0.9 to 1.8%, which is similar to that of LNG EC pill use. In comparative studies, UPA proved to be more effective than LNG EC, with the odds of pregnancy following UPA use being 65% lower within the first 24 hours following unprotected intercourse, and 42% lower up to 72 hours after unprotected intercourse, when compared to LNG EC.1 Though very widely used, many myths and misconceptions remain surrounding UPA. This contraceptive pearl aims to clarify some of those that are most common.

Which clinical conditions can/may decrease the efficacy of UPA?
Acute or chronic illnesses associated with significant vomiting or malabsorption (i.e. Celiac Disease, Bariatric Surgery, Ulcerative Colitis), may result in decreased efficacy of oral EC. As such, the CDC as well as Ella prescribing information, recommend repeat medication dosing if someone has vomited within three hours of pill intake, corresponding with the maximum amount of time necessary to achieve peak plasma concentrations.1

Patient weight and BMI may decrease the effectiveness of emergency contraception pills, with studies showing that UPA is superior to LNG EC in those who are overweight or have a BMI > 30. Please refer to this previous Contraceptive Pearl for a more in-depth review.

Are there medications that affect the use of UPA?
The mechanism of action of certain medications can reduce plasma levels of UPA, rendering it less effective. Such medication classes include seizure meds (Phenytoin, Topamax), antifungals (Griseofulvin), antibiotics (Rifampin) as well as certain supplements (St. John’s wort). If an individual is currently taking or has taken any of these medications within the past 4 weeks, an alternative non-hormonal emergency contraceptive method should be considered.1-2

Is a urine pregnancy test required prior to administering UPA?
While UPA reduces the risk of pregnancy after unprotected sexual intercourse, it does not completely remove this risk. If an individual begins menses within two weeks of UPA use, they can be reassured of their nonpregnant status. If menses does not occur, a urine pregnancy test is recommended three weeks following UPA use. It is not recommended to delay or withhold the use of UPA for pregnancy testing.1

Is it safe/okay to take UPA more than once during the same menstrual cycle?
Currently, there are no specific safety concerns regarding frequent or repeated use of UPA, nor is there evidence of increased risk of ectopic pregnancy with repeated use. Additionally, weekly use of UPA has not been associated with major adverse reactions, although headache and nausea are commonly reported. In a contraceptive study of individuals who were administered UPA 30mg orally every five to seven days, ovulation occurred in greater than 70% of menstrual cycles, likely due to UPA’s half-life of 32 hours. Thus, repeat dosing of UPA in the same cycle is not recommended by the manufacturer.1 However, given the potential risk of an undesired pregnancy, and that individuals may take UPA during times in their cycle when there is a low risk of pregnancy, repeated dosing should not be withheld. However, there should be counseling that while repeat dosing of UPA appears safe, the effectiveness of multiple doses within the same menstrual cycle remains unclear.

When should an individual resume hormonal birth control after taking UPA?
Though it has been advised to continue or initiate routine contraception use as soon as possible after the use of UPA, there are theoretical concerns that doing so may decrease its effectiveness as an emergency contraceptive method. It is recommended to delay initiation of contraceptives containing progesterone for five days and abstinence vs. a barrier method as back-up for an additional seven days or until the next menses or withdrawal bleed. Given such, the timing of hormonal contraception initiation should be obtained via shared decision-making.1,3

Is there a teratogenic risk with taking UPA when unknowingly pregnant?
For individuals who are unknowingly pregnant, there is limited, yet reassuring data regarding safety. There has been no documented or demonstrated association between embryonic exposure to contraceptive hormones/fetal malformations. Additionally, no pregnancy or delivery complications due to UPA use have been reported.

Is UPA safe for use while breastfeeding or chestfeeding?
Currently, there is minimal data available regarding the safety of using UPA during breastfeeding or chestfeeding. The general consensus is that one single dose is safe, and most medication labeling is overly cautious and more appropriate for people who take multiple doses for other indications. It is recommended to exercise caution when counseling patients regarding the practice of expressing and discarding breast/chestmilk, as it can be detrimental to breast/chestfeeding relationships. Additionally, it is recommended to engage in shared decision-making with patients who are breast/chestfeeding and interested in UPA.4

RHAP Resources:

Your Birth Control Choices Fact Sheet

Emergency Contraception: Which EC is Right for Me?

Emergency Contraception Pill User Guide


1. Salcedo J, Cleland K, Bartz D, Thompson I. Society of Family Planning Clinical Recommendations: Emergency contraception. Contraception. 2023;121(109958):109958. doi:

2. Haeger KO, Lamme J, Cleland K. State of emergency contraception in the U.S., 2018. Contraception and Reproductive Medicine. 2018;3(1). doi:

3. Salcedo J, Rodriguez MI, Curtis KM, Kapp N. When can a woman resume or initiate contraception after taking emergency contraceptive pills? A systematic review. Contraception. 2013;87(5):602-604. doi:

4. TPD App FAQs – Trash The Pump and Dump. Accessed May 16, 2024.

5. Seales S, Seales P. Emergency Contraception: Safety and Effectiveness. American Family Physician. 2020;101(11):651-652.

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