ellaOne (ulipristal acetate)

What ulipristal acetate is and how it works

Ulipristal acetate (ella/ellaOne) is a single-dose emergency contraceptive tablet taken after unprotected sex or a contraceptive failure (such as a missed pill or a broken condom), to help prevent pregnancy. It works mainly by delaying or preventing ovulation (the release of an egg). (1) (2)

It is effective for up to 120 hours (5 days) after unprotected intercourse, but works best the sooner it is taken. It is not intended for routine or repeated use as a regular contraceptive method, and it does not protect against sexually transmitted infections.

Mechanism of action: how ulipristal acetate works

Ulipristal acetate is a selective progesterone receptor modulator with partial agonist/antagonist activity at the progesterone receptor. Its primary contraceptive mechanism is inhibition or delay of ovulation via disruption of the LH surge, even in the late follicular phase, which distinguishes it from levonorgestrel (whose efficacy declines more sharply once the LH surge has begun). (1) (2)

What ulipristal acetate is used for

Before taking ulipristal acetate

Do not take / not appropriate for

• Do not take ulipristal acetate if you know or suspect you are already pregnant -- it will not end an existing pregnancy. (all countries) (1) (2)
• Do not take it if you have had a serious allergic reaction to ulipristal acetate before. (United Kingdom, European Union) (2)
• Do not rely on ulipristal acetate as your regular method of contraception, and do not take it more than once in the same menstrual cycle without checking with a pharmacist or clinician. (all countries) (1) (2)

Tell your clinician about

• Whether you have taken any hormonal contraceptive (the combined pill, progestogen-only pill, patch, ring, injection, implant, or hormonal IUD) recently, or plan to start one soon -- timing matters for both medicines to work properly.
• Whether you take any medicine for epilepsy, tuberculosis, HIV, or a fungal infection, or St. John's Wort -- some of these can make ulipristal acetate less effective.
• Whether you are breastfeeding.
• Whether you have severe asthma controlled with oral steroids, or severe liver problems.
• If you have had unprotected sex earlier in the same cycle, since this may affect suitability.

How to take ulipristal acetate

• Take the single tablet by mouth as soon as possible after unprotected sex or a contraceptive failure -- effectiveness may lessen the longer you wait, and there is no efficacy data beyond 120 hours (5 days).
• Can be taken with or without food, at any point in your menstrual cycle.
• If you vomit within 3 hours of taking it, contact a pharmacist or clinician -- another dose may be needed.
• Use a barrier method (such as condoms) for the rest of your current cycle, since ulipristal acetate does not protect against pregnancy from any further unprotected sex.
• Do not start or restart a hormonal contraceptive (the pill, patch, ring, injection, or implant) until at least 5 days after taking ulipristal acetate -- ask a pharmacist or clinician for guidance on timing.

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6)

Missed dose

This medicine is taken as a single dose, so there is no ongoing dosing schedule to miss. If you are unsure whether you took it correctly or in time, contact a pharmacist or clinician promptly.

Overdose

Taking more than one tablet is not expected to improve effectiveness and is not recommended. If you are concerned you have taken too much, contact a pharmacist, clinician, or poison-control service. (2)

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Serious warnings

Interactions

• Strong CYP3A4-inducer medicines (such as rifampicin, certain anti-seizure medicines including phenytoin and carbamazepine, and St. John's Wort) can markedly reduce how well ulipristal acetate works. If you have used one of these recently, ask a pharmacist about a copper IUD as a more reliable emergency contraception option instead. (2) (1)
• Hormonal contraceptives (the combined pill, progestogen-only pill, patch, ring, injection, or implant), including levonorgestrel-based emergency contraception, can reduce ulipristal acetate's own effectiveness if taken too close together -- do not start or resume hormonal contraception until at least 5 days after taking ulipristal acetate, and avoid combining it with levonorgestrel emergency contraception in the same cycle. (1) (2)
• Strong CYP3A4 inhibitors (such as itraconazole or ketoconazole) can raise ulipristal acetate levels in the body. (1)

Pregnancy, breastfeeding, kidney/liver function, age

Monitoring

Before starting

• Confirm timing since unprotected intercourse is within 120 hours
• Ask about recent or planned hormonal contraceptive use
• Ask about medicines that induce CYP3A4

During treatment

• Watch for severe or persistent lower abdominal pain (possible ectopic pregnancy).
• Take a pregnancy test if your period is more than about 7 days late.
• Use a barrier method until your next period, and get guidance on when to resume hormonal contraception.

Storage

Store below 25 degC, protected from light and moisture, in the original packaging, out of reach of children.

Frequently asked questions

References

1. ella (ulipristal acetate) tablet, for oral use -- full prescribing informationU.S. Food and Drug Administration / DailyMed (NIH), full prescribing information · United States · accessed 2026-07-30 · source 1
2. Ulipristal 30 mg film-coated tablets (ellaOne) -- Summary of Product Characteristicselectronic medicines compendium (emc), United Kingdom -- HRA Pharma UK · United Kingdom · accessed 2026-07-30 · source 2
3. ellaOne (ulipristal acetate) -- EPAR and CHMP prescription-status variationEuropean Medicines Agency (EMA) -- EPAR for ellaOne · European Union · accessed 2026-07-30 · source 3
4. ella (ulipristal acetate) Product MonographHealth Canada product monograph, AbbVie Corporation · Canada · accessed 2026-07-30 · source 4
5. EllaOne ulipristal acetate 30 mg tablet blister pack -- ARTG entry 219535Therapeutic Goods Administration (TGA), Australia / healthdirect.gov.au (Australian Government consumer health service) · Australia · accessed 2026-07-30 · source 5
6. Ulipristal acetate New Zealand regulatory status -- approved only as Esmya for uterine fibroids, not for emergency contraceptionMedsafe (New Zealand regulator) -- via independent clinical/regulatory summary · New Zealand · accessed 2026-07-30 · source 6

Brand names by country

Single-ingredient ulipristal acetate names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries