ellaOne (Ulipristal Acetate): Uses, Dosage & Side Effects
Emergency contraceptive pill effective for up to 5 days (120 hours) after unprotected intercourse
ellaOne is an emergency contraceptive pill containing ulipristal acetate 30 mg. It works by delaying or inhibiting ovulation to prevent pregnancy after unprotected sexual intercourse or contraceptive failure. ellaOne is effective for up to 120 hours (5 days) after unprotected sex – longer than levonorgestrel-based alternatives – and maintains consistent efficacy throughout this window. It is available without a prescription in many countries. ellaOne does not terminate an existing pregnancy and does not protect against sexually transmitted infections. Of 100 women who take ellaOne after unprotected intercourse, approximately 2 will become pregnant.
Quick Facts: ellaOne
Key Takeaways
- Effective for up to 5 days (120 hours) after unprotected sex: ellaOne can be taken up to 120 hours after intercourse, but the sooner you take it, the more effective it is. It maintains consistent efficacy throughout the full 5-day window.
- Works by delaying ovulation: Ulipristal acetate is a selective progesterone receptor modulator that prevents or delays the release of an egg, even when taken close to the expected time of ovulation.
- Does not terminate an existing pregnancy: If you are already pregnant, ellaOne will not end the pregnancy. It is designed solely to prevent a pregnancy from starting.
- May interact with hormonal contraceptives: ellaOne can temporarily reduce the effectiveness of hormonal birth control pills, patches, and rings. Use barrier methods (condoms) until your next period after taking ellaOne.
- Not a substitute for regular contraception: Emergency contraception is less effective than regular contraceptive methods and should not be used repeatedly as your primary form of birth control.
What Is ellaOne and What Is It Used For?
ellaOne is an emergency contraceptive pill (morning-after pill) containing ulipristal acetate 30 mg. It is intended to prevent pregnancy after unprotected sexual intercourse or when your regular contraceptive method has failed. It can be taken up to 120 hours (5 days) after unprotected sex.
Emergency contraception is a time-sensitive intervention used to prevent pregnancy after unprotected intercourse or contraceptive failure. ellaOne is one of the most effective oral emergency contraceptives available, distinguished by its extended 120-hour efficacy window and its ability to delay ovulation even after the luteinizing hormone (LH) surge has begun – a critical advantage over levonorgestrel-based alternatives.
You may need ellaOne in the following situations: if you had unprotected sexual intercourse without using any form of contraception; if a condom broke, slipped off, or was not used correctly; if you forgot to take your regular contraceptive pill according to its recommended schedule; if your contraceptive patch or vaginal ring was dislodged, fell out, or was not replaced on time; or in any other situation where your contraceptive method may not have worked properly.
ellaOne is suitable for all women of childbearing age, including adolescents. You can take the tablet at any point during your menstrual cycle, and it can be taken with or without food at any time of day. While it is most effective when taken as soon as possible, clinical studies confirm that its efficacy remains consistent throughout the full 5-day window, which is a significant advantage over other oral emergency contraceptives.
How ellaOne Works
The active ingredient in ellaOne, ulipristal acetate, is a selective progesterone receptor modulator (SPRM). It exerts its contraceptive effect primarily by modifying the activity of the natural hormone progesterone, which is essential for ovulation to occur. By binding to progesterone receptors with high affinity, ulipristal acetate delays or inhibits the surge in luteinizing hormone (LH) that triggers the release of an egg from the ovary.
Crucially, ulipristal acetate can delay ovulation even when LH levels have already started to rise – a stage in the menstrual cycle when levonorgestrel (the active ingredient in many other morning-after pills) is no longer effective. This pharmacological property is the key reason why ellaOne maintains its efficacy throughout the full 120-hour window, while levonorgestrel-based products become progressively less effective after 72 hours.
It is important to understand that emergency contraceptives do not always work. Among 100 women who take ellaOne after unprotected intercourse, approximately 2 will become pregnant. The medication is a contraceptive that prevents a pregnancy from beginning; it will not interrupt or terminate an existing pregnancy. Furthermore, ellaOne does not protect against sexually transmitted infections (STIs) – only condoms can provide that protection.
If you have unprotected intercourse again after taking ellaOne, the tablet will not prevent you from becoming pregnant from that subsequent encounter. You must use a barrier method of contraception (such as condoms) every time you have sex until your next menstrual period.
What Should You Know Before Taking ellaOne?
Before taking ellaOne, ensure you are not already pregnant. Do not use ellaOne if you are allergic to ulipristal acetate or any of its excipients. Tell your pharmacist or doctor if you have severe asthma, severe liver disease, or if your period is late – as you may already be pregnant.
Contraindications
You must not take ellaOne if you are allergic (hypersensitive) to ulipristal acetate or to any of the other ingredients in the tablet. The excipients include lactose monohydrate, povidone, croscarmellose sodium, and magnesium stearate. If you know you have an allergy to any of these substances, inform your pharmacist before purchasing or taking the medication.
Warnings and Precautions
Speak to your pharmacist, doctor, or healthcare provider before taking ellaOne in the following circumstances:
- If your period is late or you have symptoms of pregnancy (breast tenderness, morning nausea) – you may already be pregnant. ellaOne will not work if you are already pregnant, and you should take a pregnancy test before using it.
- If you suffer from severe asthma: There is limited data on the use of ulipristal acetate in women with severe asthma. Discuss alternatives with your doctor.
- If you have severe liver disease: The metabolism of ulipristal acetate may be affected, and the drug has not been specifically studied in this population.
All women should take emergency contraception as soon as possible after unprotected intercourse for maximum effectiveness. There is some data suggesting that ellaOne may be less effective with increasing body weight or Body Mass Index (BMI), but these data are limited and inconclusive. The European Medicines Agency (EMA) and the World Health Organization (WHO) recommend that ellaOne should be offered to all women regardless of their weight or BMI, as the benefits of preventing an unintended pregnancy outweigh the theoretical reduction in efficacy.
If you become pregnant despite taking ellaOne, contact your doctor. As with any pregnancy, your doctor may want to check that the pregnancy is not ectopic (developing outside the uterus). This is particularly important if you experience severe abdominal pain or abnormal bleeding, or if you have a history of ectopic pregnancy, previous tubal surgery, or chronic pelvic inflammatory disease.
Pregnancy and Breastfeeding
Pregnancy: If your period is late, take a pregnancy test or speak with your pharmacist or doctor before taking ellaOne to confirm you are not already pregnant. ellaOne is a contraceptive used to prevent a pregnancy from beginning – it will not terminate an existing pregnancy. If you become pregnant despite taking ellaOne, there is no evidence that the medication will harm your pregnancy. However, it is important to contact your doctor for appropriate follow-up care, including ruling out ectopic pregnancy.
Breastfeeding: If you take ellaOne while breastfeeding, you should not breastfeed your baby for one week after taking the tablet. During this week, it is recommended that you use a breast pump to maintain your milk supply, but discard the expressed milk. The effects of ulipristal acetate on a breastfed infant have not been fully established, and this precaution is advised to minimise any potential exposure.
Fertility: ellaOne does not affect your future fertility. It acts only within the current menstrual cycle by delaying ovulation. After taking the tablet, your fertility returns to normal. If you have unprotected intercourse after taking ellaOne, you can still become pregnant. Use condoms or another barrier method until your next period.
How Does ellaOne Interact with Other Drugs?
ellaOne can interact with hormonal contraceptives, levonorgestrel-based emergency contraceptives, and drugs that induce the CYP3A4 enzyme (such as certain epilepsy medications, rifampicin, and St John’s Wort). These interactions can reduce the effectiveness of ellaOne.
Drug interactions are an important consideration when using ellaOne, as certain medications can significantly reduce its effectiveness. Ulipristal acetate is metabolised primarily by the cytochrome P450 enzyme CYP3A4, and medications that induce or inhibit this enzyme can alter its plasma levels and clinical efficacy.
Major Interactions
The following medications may make ellaOne less effective. If you have used any of these drugs within the past 4 weeks, your doctor may recommend an alternative form of emergency contraception, such as a copper intrauterine device (IUD):
| Drug / Class | Examples | Interaction Effect |
|---|---|---|
| Epilepsy medications | Phenytoin, fosphenytoin, phenobarbital, primidone, carbamazepine, oxcarbazepine, barbiturates | CYP3A4 inducers – may reduce ulipristal acetate plasma levels and decrease efficacy |
| Tuberculosis medications | Rifampicin, rifabutin | Potent CYP3A4 inducers – can significantly reduce ulipristal acetate effectiveness |
| HIV medications | Ritonavir, efavirenz, nevirapine | CYP3A4 inducers or inhibitors – may alter ulipristal acetate levels unpredictably |
| Antifungal medications | Griseofulvin | CYP3A4 inducer – may reduce effectiveness of ellaOne |
| Herbal preparations | St John’s Wort (Hypericum perforatum) | Potent CYP3A4 inducer – can significantly reduce ulipristal acetate levels |
Interactions with Hormonal Contraceptives
ellaOne may temporarily reduce the effectiveness of hormonal contraceptives, including combined oral contraceptive pills, progestogen-only pills, contraceptive patches, and vaginal rings. This occurs because ulipristal acetate and progestogen compete for the progesterone receptor. If you use hormonal contraceptives, you should continue taking them as normal after using ellaOne, but you must also use a barrier method (condoms) every time you have intercourse until your next period.
Do not take ellaOne together with a levonorgestrel-based emergency contraceptive (such as Levonelle or Plan B). If both medications are taken together, the effectiveness of ellaOne may be reduced, as levonorgestrel and ulipristal acetate have opposing actions at the progesterone receptor.
What Is the Correct Dosage of ellaOne?
The dosage of ellaOne is one single 30 mg tablet taken by mouth as soon as possible after unprotected intercourse, and no later than 120 hours (5 days) afterward. It can be taken with or without food, at any time of day, and at any point in your menstrual cycle.
Standard Dosage
All Women of Childbearing Age (Including Adolescents)
Take one tablet (30 mg ulipristal acetate) by mouth as a single dose. Take it as soon as possible after unprotected intercourse. Do not delay – while ellaOne is effective for up to 120 hours, earlier administration maximises effectiveness.
- Can be taken with or without food
- Can be taken at any time during the menstrual cycle
- Can be taken at any time of day
If You Vomit After Taking ellaOne
If you vomit within 3 hours of taking the tablet, take another tablet as soon as possible. Vomiting shortly after ingestion may prevent the medication from being fully absorbed into the bloodstream, potentially reducing its effectiveness. If vomiting persists, contact your pharmacist or doctor for advice – a copper IUD may be recommended as an alternative.
Missed Dose
The concept of a missed dose does not apply to ellaOne, as it is a single-dose medication. However, the principle of timing is critical: the sooner you take it after unprotected intercourse, the more effective it will be. If you realise after the 120-hour window has passed that you needed emergency contraception, contact your doctor or healthcare provider to discuss your options.
If Your Next Period Is Late
After taking ellaOne, it is normal for your next period to be a few days earlier or later than expected. However, if your period is more than 7 days late, or if it is unusually light or heavy, or if you experience symptoms such as abdominal pain, breast tenderness, nausea, or vomiting, you may be pregnant. You should take a pregnancy test promptly and contact your doctor if the result is positive.
Overdose
There have been no reports of serious adverse effects from taking higher than recommended doses of ellaOne. However, if you have taken more than one tablet, or if someone else has accidentally taken ellaOne, contact your pharmacist or doctor for advice. The experience with ulipristal acetate overdose is limited, but based on the known safety profile, serious toxicity is considered unlikely.
What Are the Side Effects of ellaOne?
Like all medicines, ellaOne can cause side effects, although not everyone experiences them. The most common side effects include nausea, abdominal pain, headache, painful periods, and fatigue. Most side effects are mild and resolve on their own within a few days.
The following side effects have been reported in clinical studies and post-marketing surveillance. Some symptoms, such as breast tenderness, nausea, and abdominal pain, can also be early signs of pregnancy. If your period does not arrive and you experience these symptoms after taking ellaOne, you should take a pregnancy test.
Common Side Effects
May affect up to 1 in 10 users
- Nausea
- Abdominal (stomach) pain or discomfort
- Vomiting
- Painful menstrual periods (dysmenorrhoea)
- Pelvic pain
- Breast tenderness
- Headache
- Dizziness
- Mood changes
- Muscle pain (myalgia)
- Back pain
- Fatigue (tiredness)
Uncommon Side Effects
May affect up to 1 in 100 users
- Diarrhoea, heartburn, flatulence, dry mouth
- Abnormal or irregular vaginal bleeding
- Heavy or prolonged menstrual bleeding
- Premenstrual syndrome
- Vaginal irritation or discharge
- Decreased or increased libido
- Hot flushes
- Appetite changes, emotional disturbance, anxiety, restlessness
- Sleep disturbances, drowsiness, migraine, visual disturbances
- Influenza-like symptoms
- Acne, skin complaints, itching
- Fever, chills, malaise
Rare Side Effects
May affect up to 1 in 1,000 users
- Genital pain or itching, pain during intercourse
- Rupture of an ovarian cyst
- Unusually light menstrual periods
- Difficulty concentrating, vertigo, tremor, disorientation, fainting
- Abnormal eye sensation, red eyes, photosensitivity
- Dry throat, taste disturbances
- Allergic reactions (rash, urticaria, facial swelling)
- Thirst
Contact your doctor or pharmacist immediately if you experience signs of a severe allergic reaction, such as swelling of the face, lips, tongue, or throat, difficulty breathing, or widespread rash with itching. While severe allergic reactions to ellaOne are very rare, they require prompt medical attention.
Driving and Operating Machinery
Some women experience dizziness, drowsiness, blurred vision, or difficulty concentrating after taking ellaOne. If you experience any of these symptoms, do not drive or operate machinery until the symptoms have resolved.
How Should You Store ellaOne?
Store ellaOne in its original packaging, out of reach of children. No special temperature storage conditions are required. Check the expiry date before taking the tablet – do not use it after the stated expiry date.
Keep the tablet in its original blister pack until you are ready to take it. Store it in a place where children cannot see or reach it. ellaOne does not require any special storage conditions regarding temperature or humidity. However, as with all medicines, store it in a dry place and away from direct sunlight.
Check the expiry date printed on the carton and blister pack before use. The expiry date refers to the last day of the stated month. Do not take ellaOne after this date, as the medication may have degraded and its effectiveness cannot be guaranteed.
Do not dispose of medicines by flushing them down the toilet or throwing them in household waste. Return unused or expired medications to your local pharmacy for safe disposal. This helps to protect the environment.
What Does ellaOne Contain?
Each ellaOne film-coated tablet contains 30 mg of ulipristal acetate as the active ingredient, along with inactive excipients including lactose monohydrate and various film-coating agents.
Active Ingredient
Each film-coated tablet contains 30 milligrams of ulipristal acetate. Ulipristal acetate is a selective progesterone receptor modulator that exerts its emergency contraceptive effect by delaying or inhibiting ovulation.
Inactive Ingredients (Excipients)
The other ingredients serve to give the tablet its structure, aid absorption, and provide the protective film coating:
- Tablet core: Lactose monohydrate, povidone, croscarmellose sodium, magnesium stearate
- Film coating: Poly(vinyl alcohol) (E1203), macrogol (E1521), talc (E553b), titanium dioxide (E171), polysorbate 80 (E433), iron oxide yellow (E172), potassium aluminium silicate (E555)
ellaOne contains lactose monohydrate. If you have been told by your doctor that you have an intolerance to some sugars, contact your doctor before taking this medicine.
This medicine contains less than 1 mmol (23 mg) sodium per tablet, which means it is essentially sodium-free.
Appearance
ellaOne is a gold-coloured, round, shield-shaped film-coated tablet approximately 10.8 mm in diameter, debossed with “ella” on both sides. It is supplied in a carton containing one blister pack with a single tablet.
Manufacturer
ellaOne is manufactured by Laboratoire HRA Pharma (Paris, France) and distributed internationally. Manufacturing sites include Cenexi (Osny, France) and Delpharm Lille S.A.S. (Lys-Lez-Lannoy, France).
Frequently Asked Questions About ellaOne
ellaOne can be taken up to 120 hours (5 days) after unprotected sexual intercourse or contraceptive failure. However, it is most effective when taken as soon as possible. Studies show that ellaOne maintains consistent efficacy throughout the full 120-hour window, unlike levonorgestrel-based emergency contraceptives which become significantly less effective after 72 hours. If more than 5 days have passed, contact your doctor to discuss alternatives such as a copper IUD, which can be inserted up to 5 days after unprotected intercourse or up to 5 days after the earliest estimated date of ovulation.
ellaOne contains ulipristal acetate, a selective progesterone receptor modulator, while other morning-after pills (such as Levonelle, NorLevo, or Plan B) contain levonorgestrel. The key differences are: ellaOne is effective for up to 120 hours (5 days) compared to 72 hours (3 days) for levonorgestrel; ellaOne maintains its effectiveness throughout the 5-day window, whereas levonorgestrel becomes less effective over time; and ellaOne can delay ovulation even after the LH surge has begun, when levonorgestrel is no longer effective. It is important not to take both pills together as this may reduce the efficacy of ellaOne.
No, ellaOne does not affect your future fertility. It is a single-dose emergency contraceptive that works by delaying ovulation in the current menstrual cycle only. After taking ellaOne, your fertility returns to normal. However, if you have unprotected intercourse after taking the tablet, you can still become pregnant from that subsequent encounter. Use a barrier method (condoms) until your next period. If you wish to start or continue using a regular contraceptive method, you may do so, but also use condoms until your next period.
If you take ellaOne while breastfeeding, you should not breastfeed for one week after taking the tablet. During this time, it is recommended to express and discard breast milk using a breast pump to maintain your milk production. The effects of ulipristal acetate on a breastfed infant are not fully known, so this precaution is advised to minimise any potential exposure to the infant through breast milk.
There is some data suggesting that ellaOne may be less effective with increasing body weight or BMI. However, these data are limited and inconclusive. Both the European Medicines Agency (EMA) and the World Health Organization (WHO) recommend that ellaOne should be offered to all women regardless of their weight or BMI, as the benefits of preventing an unintended pregnancy outweigh the potential for slightly reduced efficacy. If you have concerns about your weight and emergency contraception effectiveness, speak with your pharmacist or doctor, who may also discuss the copper IUD as a highly effective weight-independent alternative.
No, ellaOne should not be used as a regular method of contraception. It is designed for emergency use only. Emergency contraception is less effective than regular contraceptive methods and does not provide ongoing protection against pregnancy. If you do not currently use a regular contraceptive, or if your current method does not suit your needs, speak with your doctor, pharmacist, or healthcare provider about options such as the combined pill, progestogen-only pill, contraceptive patch, vaginal ring, contraceptive implant, or intrauterine device (IUD).
References
- European Medicines Agency (EMA). ellaOne – Summary of Product Characteristics. Last updated 2024. Available at: ema.europa.eu/en/medicines/human/EPAR/ellaone
- World Health Organization (WHO). Emergency Contraception – Fact Sheet. 2024. Available at: who.int/news-room/fact-sheets/detail/emergency-contraception
- Faculty of Sexual & Reproductive Healthcare (FSRH). FSRH Clinical Guideline: Emergency Contraception. 2023 Update. Available at: fsrh.org
- Glasier AF, Cameron ST, Fine PM, et al. Ulipristal acetate versus levonorgestrel for emergency contraception: a randomised non-inferiority trial and meta-analysis. The Lancet. 2010;375(9714):555–562. doi:10.1016/S0140-6736(10)60101-8
- Brache V, Cochon L, Jesam C, et al. Immediate pre-ovulatory administration of 30 mg ulipristal acetate significantly delays follicular rupture. Human Reproduction. 2010;25(9):2256–2263. doi:10.1093/humrep/deq157
- American College of Obstetricians and Gynecologists (ACOG). Practice Bulletin No. 152: Emergency Contraception. 2015 (Reaffirmed 2022).
- International Consortium for Emergency Contraception (ICEC). Emergency Contraceptive Pills: Medical and Service Delivery Guidance. 4th edition. 2018.
- Moreau C, Trussell J. Results from pooled Phase III studies of ulipristal acetate for emergency contraception. Contraception. 2012;86(6):673–680. doi:10.1016/j.contraception.2012.05.012
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