Ulipristal acetate (Ellaone)

What is it used for?

  • Emergency contraception within five days (120 hours) of unprotected sex.

EllaOne is known as a 'morning after pill'. It is used to reduce the chances of becoming pregnant after unprotected sex or failure of a contraceptive method.

How does it work?

EllaOne tablets contain the active ingredient ulipristal acetate, which is a selective progesterone receptor modulator. It works by acting on the body's receptors for the naturally occurring female sex hormone, progesterone.

It is not fully understood how this medicine prevents pregnancy. It is thought to work by preventing ovulation and fertilisation and also by altering the lining of the womb, depending on which stage of the menstrual cycle the woman is at.

In a woman's normal menstrual cycle, an egg matures and is released from the ovaries (ovulation). The ovary then produces progesterone, which prevents the release of further eggs. Ulipristal tricks the body processes into thinking that ovulation has already occurred. This prevents the release of eggs from the ovaries.

Ulipristal also increases the thickness of the natural mucus at the neck of the womb (cervix), making it more difficult for sperm to cross from the vagina into the womb. By preventing sperm entering the womb, successful fertilisation of any egg that is there is less likely.

Ulipristal is also thought to alter the lining of the womb, preventing it from being prepared for a fertilised egg. This means that if an egg is released from the ovaries and is fertilised, it cannot implant into the womb and therefore pregnancy is avoided.

The whole process from fertilisation to implantation in the womb can take up to five days, so EllaOne can only stop pregnancy from occurring for up to 120 hours after unprotected sex. The sooner it is taken after unprotected sex, the more effective it will be.

It is estimated that for every 100 women who take EllaOne up to five days after unprotected sex, approximately two women will become pregnant. The tablet is more effective at preventing pregnancy the earlier it is taken, so it is important to take it as soon as possible after unprotected sex, rather than delay it to the fifth day.

How do I take it?

There is one tablet to be taken. It should be taken as soon as possible after unprotected sex, and no later than 120 hours (5 days) after.

If you are sick within three hours of taking the tablet, another one should be taken immediately. You should consult your doctor, pharmacist or family planning clinic for advice and to get another tablet.


  • You will be asked about your last period and when you last had sex in order to make sure this medicine is suitable for you. This medicine can be used at any point during your menstrual cycle, but not if your period is late. If it is late, or your last period was more than five days late or unusually light or heavy, you should tell your doctor, as you may already be pregnant and this medicine will not work.
  • This medicine might make your next period earlier or later than expected by a few days. If your next period after taking this medicine is more than seven days late, or is abnormal in any way, you should consult your doctor for a pregnancy test.
  • This medicine will not always prevent a pregnancy. If you do become pregnant after taking this medicine there is a possibility that the pregnancy will be ectopic (ie occuring in the Fallopian tubes rather than the womb). For this reason, you should consult your doctor if you experience any sudden or abnormal abdominal pain after taking this medicine, and if your next period is shorter or lighter than your normal period.
  • This medicine does not provide continued contraception to prevent pregnancy after you have taken it. You should talk ask your doctor or family planning clinic for advice about regular methods of contraception.
  • It is recommended that after taking this medicine you use a barrier method of contraception such as a condom or cap, until you have your next period. This is also recommended even if you are using hormonal contraception such as the pill, because this medicine can make these methods less effective (see the end of this page for more details about this.)
  • This medicine should only be used as an emergency measure. It is not recommended for repeated use, because it is possible that it could disrupt your menstrual cycle.
  • Emergency contraception does not protect you from sexually transmitted infections.

Use with caution in

  • Severe asthma.

Not to be used in

  • Known or suspected pregnancy (see below).
  • This medicine is not recommended for women with severely decreased liver function.
  • The safety and efficacy of this medicine in girls under 18 years of age has not been studied by the manufacturer.
  • Rare hereditary problems of galactose intolerance, Lapp lactase deficiency or glucose-galactose malabsorption (EllaOne tablets contain lactose).

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.

If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

  • This medicine should not be taken by women who are pregnant. If you think you could be pregnant, if your period is late, or if your last period was more than five days late or unusually light or heavy, you should tell your doctor, as you may already be pregnant. Taking this medicine if you are already pregnant will not stop the pregnancy.
  • Emergency contraception does not prevent a pregnancy in every instance. If this medicine doesn't work to prevent a pregnancy, limited data suggest that it does not have adverse effects on a pregnancy that develops in your womb. However, as there is a possibility that a pregnancy will be ectopic after taking this medicine, you should consult your doctor immediately if you think you could be pregnant. Ask your doctor, pharmacist or family planning clinic for more information.
  • It is not known whether this medicine passes into breast milk. It is recommended that women who are breastfeeding should not breastfeed for 36 hours after taking an EllaOne tablet. You should breastfeed your baby just before taking the tablet. You can then use a breast pump to extract milk and discard it. Breastfeeding can then be continued after 36 hours.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

Very common (affect more than 1 in 10 people)

  • Headache.
  • Abdominal pain.
  • Nausea.

Common (affect between 1 in 10 and 1 in 100 people)

  • Changes in mood.
  • Dizziness.
  • Vomiting.
  • Period pain.
  • Muscle, back or pelvic pain.
  • Fatigue.
  • Breast tenderness.

Uncommon (affect between 1 in 100 and 1 in 1000 people)

  • Menstrual spotting.
  • Premenstrual syndrome.
  • Vaginal discharge.
  • Anxiety.
  • Difficulty sleeping (insomnia).
  • Changes in sex drive.
  • Hot flush.
  • Blurred vision.
  • Indigestion.
  • Dry mouth.
  • Irritability.
  • Feeling generally unwell (malaise).
  • Itching.
  • Migraine.

Rare (affect between 1 in 1000 and 1 in 10,000 people)

  • Genital itching.
  • Painful sex.
  • Spinning sensation.
  • Tremor.
  • Dry throat.
  • Cough.
  • Kidney problems, such as coloured urine, kidney stones or pain.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you take this medicine, to make sure that the combination is safe.

This morning after pill may be less effective if you are taking any of the following medicines, because these medicines speed up the breakdown of ulipristal by the liver:

  • aprepitant
  • bosentan
  • barbiturates
  • carbamazepine
  • eslicarbazepine
  • nevirapine
  • oxcarbazepine
  • phenobarbital
  • phenytoin
  • primidone
  • rifampicin
  • rifabutin
  • protease inhibitors such as ritonavir
  • the herbal remedy St John's wort (Hypericum perforatum)
  • topiramate.

If you are taking any of these medicines regularly, or have stopped taking one of them within the last 28 days, you may be advised to have a copper coil (IUD) fitted as emergency contraception, as this will not be affected by the medicines you are taking. You should discuss your options with your doctor, pharmacist or family planning clinic.

Medicines used to reduce acidity in the stomach, for example proton pump inhibitors such as omeprazole or lansoprazole, H2 antagonists such as ranitidine or cimetidine, or antacids, can reduce the absorption of ulipristal from the gut and thus make it less effective. If you take any of these medicines you should use a different morning after pill or a copper coil as emergency contraception. For more advice talk to your doctor or family plannig clinic.

EllaOne should not be taken together with emergency contraceptives containing levonorgestrel (Levonelle one step or Levonelle 1500). It won't have a combined effect with these, in fact EllaOne is likely to make Levonelle less effective.

As it acts on progesterone receptors, taking EllaOne may temporarily make regularly used hormonal contraceptives less effective. It is important to use a reliable barrier method of contraception, such as a condom, after taking EllaOne, while continuing with your usual contraceptive. If you are taking a combined pill you should use extra contraception for 14 days after taking EllaOne. (If you are taking Qlaira you should use extra contraception for 16 days.) If you are taking a progesterone-only pill (mini pill) you should use an additional method of contraception for 9 days after taking EllaOne. If you are using the vaginal ring, patch, implant or injection, you should use extra contraception for 14 days after taking EllaOne. For further advice talk to your pharmacist or family planning clinic.

Other medicines containing the same active ingredient

There are currently no other medicines available in the UK that contain ulipristal acetate as the active ingredient.