ulipristal acetate (ellaOne) postcoital contraception

Last edited 03/2021

  • Ulipristal acetate (ellaOne)
    • is a selective progesterone-receptor modulator that seems to be as effective as levonorgestrel for prevention of pregnancy. Ulipristal acetate may be used up to 120h after unprotected sexual intercourse or contraceptive failure
    • it is orally active and taken as a single dose

Mechanism of Action

  • ulipristal acetate (also known as CDB-2914 and VA2914) is a synthetic steroid derived from 19-norprogesterone
    • is a selective progesterone receptor modulator (SPRM), a class of compounds that exert tissue-selective full agonist, antagonist or partial agonist effects at the progesterone receptor
    • ulipristal has been described as a second-generation SPRM. In vivo, ulipristal has much weaker antiglucocorticoid activity than mifepristone as a result of differences in their active metabolites
  • primary mechanism of action is thought to be inhibition or delay of ovulation. A single midfollicular dose has been shown to suppress growth of lead follicles
    • administration just before, or in some cases just after, the luteinising hormone surge can inhibit follicular rupture
  • endometrial changes may also play a role. Early luteal administration of ulipristal results in delayed endometrial maturation and alterations in progesterone-dependent markers of implantation
    • a mid-luteal dose has been shown to induce early endometrial bleeding in a dose-dependent manner
    • postulated that alterations to the endometrium may inhibit implantation by rendering the uterus less receptive to the trophoblast. However, it is not known if ulipristal has a direct endometrial effect or if the observed changes are a result of an ovarian effect

Dose and frequency of administration (4)

  • One tablet (30mg) as a single dose taken as soon as possible up to 120 hours after UPSI.

Duration of Treatment (4)

  • A single dose is permitted
  • If vomiting occurs within 3 hours of ulipristal being taken a repeat dose can be supplied
  • Repeated doses can be given within the same cycle. Please note:
    • If within 7 days of previous levonorgestrel offer levonorgestrel again (not ulipristal)
    • If within 5 days of ulipristal then offer ulipristal again (not levonorgestrel)

Criteria for exclusion (4)

    • Informed consent not given. 
    • Individuals under 16 years old and assessed as lacking capacity to consent using the Fraser Guidelines.
    • Individuals 16 years of age and over and assessed as lacking capacity to consent.
    • This episode of UPSI occurred more than 120 hours ago. N.B. A dose may be given if there have been previous untreated or treated episodes of UPSI within the current cycle if the most recent episode of UPSI is within 120 hours.
    • Known or suspected pregnancy (N.B. a previous episode of UPSI in this cycle is not an exclusion. Consider pregnancy test if more than three weeks after UPSI and no normal menstrual period).
    • Less than 21 days after childbirth.
    • Less than 5 days after miscarriage, abortion, ectopic pregnancy or uterine evacuation for gestational trophoblastic disease (GTD).
    • Known hypersensitivity to the active ingredient or to any component of the product - see Summary of Product Characteristics
    • Use of levonorgestrel or any other progestogen in the previous 7 days (i.e. hormonal contraception, hormone replacement therapy or use for other gynaecological indications).
    • Concurrent use of antacids, proton-pump inhibitors or H2-receptor antagonists.
    • Severe asthma controlled by oral glucocorticoids.
    • Individuals using enzyme-inducing drugs/herbal products or within 4 weeks of stopping.
    • Acute porphyria

Cautions including any actions to be taken (4):

  • All individuals should be informed that insertion of a copper intrauterine device (Cu-IUD) within five days of UPSI or within five days from earliest estimated ovulation is the most effective method of emergency contraception. If a Cu-IUD is appropriate and acceptable supply oral EC and refer to the appropriate health service provider

  • Ulipristal is ineffective if taken after ovulation

  • If individual vomits within three hours from ingestion, arepeat dose may be given

  • Body Mass Index (BMI) >26kg/m2 or weight >70kg - individuals should be advised that though oral EC methods may be safely used, a high BMI may reduce the effectiveness. A Cu-IUD should be recommended as the most effective method of EC

  • Consideration should be given to the current disease status of those with severe malabsorption syndromes, such as acute/active inflammatory bowel disease or Crohn's disease. Although the use of ulipristal is not contra-indicated it may be less effective and so these individuals should be advised that insertion of Cu-IUD would be the most effective emergency contraception for them and referred accordingly if agreed

  • Breast feeding - advise to express and discard breast milk for 7 days after ulipristal dose
  • The effectiveness of ulipristal can be reduced by progestogen taken in the following 5 days and individuals must be advised not to take progestogen containing drugs for 5 days after ulipristal

  • If the individual is less than 16 years of age an assessment based on Fraser guidelines must be made and documented

  • If the individual is less than 13 years of age the healthcare professional should speak to local safeguarding lead and follow the local safeguarding policy

  • If the individual has not yet reached menarche consider onward referral for further assessment or investigation

Side effects or safety issues:

  • most commonly reported side effects are abdominal pain and menstrual disorders (irregular vaginal bleeding, premenstrual syndrome, uterine cramps)
  • study data have shown that the post-treatment cycle length is on average 2.9 days longer than the expected length
  • some 7% of women reported a shortened cycle, and 19.2% reported an increase in cycle length of more than 7 days
  • have been no associated adverse outcomes in the small numbers of inadvertent pregnancies that have occurred to date. The manufacturer has put a variety of measures in place to monitor outcomes of exposure during pregnancy

Drug interactions:

  • Ulipristal is metabolised via cytochrome P450, in particular CYP3A4

    Liver enzyme inducers

    • CYP3A4 inducers (e.g. rifampicin, phenytoin, carbamazepine, ritonavir, St John's wort) may reduce plasma concentrations of ulipristal and may reduce efficacy - see linked item below for further information

    Liver enzyme inhibitors

    • The effect of CYP3A4 inhibitors (e.g. ketoconazole, itraconazole, clarithromycin) may increase exposure to ulipristal, but the significance is uncertain

    Drugs that increase gastric pH

    • Use of ulipristal with antacids, proton pump inhibitors and H2 receptor antagonists, or any other drugs that increase gastric pH, may reduce absorption of ulipristal and decrease efficacy

    Other contraceptives

    • Ulipristal binds to progesterone receptors and so may reduce the efficacy of progestogen-containing contraceptives.


  • 1)Creinin MD et al. Progesterone receptor modulator for emergency contraception: a randomized controlled trial. Obstet Gynecol 2008;108:1089-1097
  • 2) Fine P et al. Ulipristal acetate taken 48-120 hours after intercourse for emergency contraception. Obstet Gynecol. 2010 Feb;115(2 Pt 1):257-63.
  • 3) FSRH (October 2009). Ulipristal Acetate (ellaOne®) - product review
  • 4) Patient Group Direction (PGD) (NHS Specialist Pharmacy Service). Supply and/or administration of ulipristal acetate 30mg tablet for emergency contraception (Accessed 17th March 2021).