Emergency Contraception

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PatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

Emergency contraception (EC) describes the use of contraceptive measures to prevent pregnancy occurring after intercourse has taken place.

In the UK three forms of EC are currently recommended:

  • An oral progestogen-only emergency contraceptive (POEC) - levonorgestrel (LNG).
  • A selective progesterone receptor modulator (SPRM) - ulipristal acetate (UPA).[1]
  • A copper intrauterine contraceptive device (Cu-IUCD).

Combined oestrogen and progestogen preparations were previously used (the Yupze method); however, studies showed increased effectiveness and acceptability of the POEC.[2] This is therefore no longer a standard method of emergency contraception.

Mifepristone may also be used for EC but is not licensed for this use in the UK.[3] 

Important points to note about EC:[4] 

  • It is not considered an abortifactant (a Judicial Review in 2002 ruled that pregnancy begins at implantation, not at fertilisation).
  • There is no time in the menstrual cycle when there is no risk of pregnancy following unprotected sexual intercourse (UPSI), particularly in an irregular cycle. Conception has been recorded as occurring on all days in a cycle, but is extremely unlikely to occur in the first three days.
  • A Cu-IUCD is the most effective form of EC and should be offered to all women, even if they present within 72 hours.

When no contraception has been used

  • Following consensual sexual intercourse.
  • Following rape or sexual assault.

When there is contraceptive failure or incorrect use

  • Incorrect use or failure of barrier methods such as the condom, diaphragm or cap.
  • Failed coitus interruptus (ejaculation into vagina or on to external genitalia).
  • Miscalculation of the fertile time, or failure to abstain/withdraw/use barrier methods during this time, when using natural family planning methods.
  • IUCD/intrauterine system (IUS) expulsion (if complete or partial expulsion has occurred or if it is necessary to remove the device mid-cycle and there has been UPSI within the previous five days).
  • Whilst using any form of oral hormonal contraception if UPSI has occurred whilst taking, or within 28 days after taking, enzyme-inducing agents such as rifampicin. (In this situation, the Cu-IUCD should be offered. If using LNG, a double dose of 3 mg should be used. UPA should not be used with enzyme-inducing drugs.)
  • Following incorrect use or potential failure of hormonal method of contraception as outlined below.
Hormonal contraception used
Possible indications for emergency contraception
Combined oral contraception
  • If two or more pills have been missed in the first seven days of the packet and unprotected sexual intercourse (UPSI) has taken place in these seven days or in the seven-day pill-free interval.
  • If UPSI takes place without the use of an additional barrier method of contraception during an episode of vomiting or severe diarrhoea which has lasted more than 24 hours (as per missed pill advice).
  • In all cases, additional barrier methods are needed for seven days (nine days for Qlaira®) if levonorgestrel (LNG) is used, whilst continuing normal pill taking. If ulipristal acetate (UPA) is used, additional barrier methods are needed for 14 days (16 days for Qlaira®).
  • If more than two pills are missed during the last seven days of the packet, the next packet should be started immediately without a seven-day pill-free interval. The pill-free interval will be shorter and the woman will be more protected than usual. Emergency contraception (EC) is very rarely indicated for pills missed on days 15-21.
  • Advice for Qlaira® and Zoely® differs, and manufacturers' advice should be followed.
  • (See separate article Missed Contraceptive Pills for more detail.)
Progestogen-only contraception
  • If one or more pill has been missed or taken more than three hours late (>12 hours late for desogestrel-containing pills), and UPSI has occurred in the 2-3 days prior to the missed pill, or before two further tablets have been correctly taken.
  • Additional barrier methods are required whilst continuing the normal progestogen-only pill regime. This should be for two days following use of LNG, and nine days following use of UPA.
Medroxyprogesterone acetate (Depo-Provera®)
  • If UPSI has taken place >14 weeks after the last injection.
  • If additional contraceptive precautions have not been used or have failed, and UPSI has taken place when starting the injection during the time that additional precautions are required.
Contraceptive patches
  • If application of a new patch at the start of a cycle is delayed by more than 48 hours and UPSI has occurred. A new 'Day 1' patch should be applied as soon as remembered
  • If the patch lifts partially or completely for more than 48 hours, or if there is a delay of more than 48 hours in changing patches at the end of week 1 or week 2,
  • Following use of EC pills, advise additional barrier methods for seven days if LNG is used, and for 14 days if UPA is used.
Combined contraceptive vaginal ring
  • The ring is expelled for more than three hours during the first or second week of use and UPSI or barrier failure occurs in the seven days following this.
  • The ring is found to be broken during use, and UPSI has occurred in the previous five days or UPSI or barrier failure occurs in the seven days following this.
  • The ring is not immediately replaced after the seven-day ring-free break, and UPSI occurs during the ring-free interval.
  • If an EC pill has been taken, and the ring re-inserted, additional contraceptive precautions should be taken for seven days if LNG has been used, and for 14 days if UPA has been used.
Contraceptive implant
  • If additional contraceptive precautions have not been taken when starting the method at a time when they were required, and if UPSI has taken place.
  • If UPSI has taken place whilst taking enzyme-inducing drugs, or in the 28 days thereafter
Intrauterine system (IUS)
  • Unprotected sexual intercourse has occurred in the five days prior to removal, perforation, or partial or complete expulsion of the IUS.
  • If additional contraceptive precautions have not been taken when starting the method at a time when they were required, and if UPSI has taken place.

Before making a shared decision with the patient as to the appropriate form of EC, a full history should be taken with particular reference to:

  • Discuss what time has elapsed since unprotected intercourse.
  • Note what contraception was used at the time of intercourse, if any.
  • Go through menstrual history:
    • What was the date of the last menstrual period?
    • Was the last period normal?
    • What is the usual cycle length?
    • Is ovulation likely to have taken place yet this cycle? (If the normal cycle is 28 days, ovulation is thought to occur around day 14).
    • Could implantation of a fertilised ovum have occurred this cycle? (Implantation occurs no earlier than five days after ovulation. To calculate the likely date of implantation, subtract 14 days from the date of the expected date of the next period and add five days).
  • Note whether there has been any other unprotected intercourse this cycle and whether the woman might already be pregnant.
  • Establish whether there has been any previous use of EC.
  • Ask whether the woman is breast-feeding.
  • Discuss obstetric and gynaecological history (with particular attention to history of pelvic inflammatory disease (PID), current vaginal discharge, history of ectopic pregnancy).
  • Discuss current requirement for contraception.
  • Note medications used - eg, enzyme-inducing agents such as phenytoin (ask about over-the-counter enzyme inducers such as St John's wort).
  • Take account of general health, looking for any contra-indications - eg, liver disease, porphyria.
  • Sexual history - consider the risk of sexually transmitted infection (STI).

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Mode of action

  • When used early in the cycle, it is thought that progestogen-only emergency contraception (POEC) inhibits ovulation. When used later in the cycle, it is unclear how it has its effect.[4]


  • POEC should be given in the form of LNG 1.5 mg, taken as soon as possible after UPSI.
  • It is now available to buy over-the-counter without prescription for those aged 16 years or more, in addition to being a prescribable drug.
  • There are several available brands, taken as a single 1.5 mg dose (World Health Organization (WHO) recommended regimen).[6] Some can be bought from pharmacies. Some are prescription-only medicines.

Timing of use

  • Licensed for use within 72 hours of UPSI.
  • Use beyond 72 hours is unlicensed, but consider use between 72-120 hours if the other forms of EC cannot be used.[5] It may still have some efficacy at this time, although it will be less effective than if it is taken within 72 hours.[7] 
  • POEC can be used more than once in a cycle if appropriate and repeated use will not induce abortion if the woman is already pregnant. This is supported by the Faculty of Sexual and Reproductive Healthcare.[4]


  • Efficacy rates are difficult to establish and compare. Comparison has to be made with the number of women who would become pregnant after a single episode of UPSI without EC, which is variably reported as 5.5-8%. Pregnancy rates following a single episode of UPSI for women taking levonorgestrel emergency contraception (LNG-EC) are 1.1-2.6%.[8] [9] i.e. If 1,000 women had unprotected sex once, around 60 to 80 would become pregnant. If all those women had taken Levonelle®, only around 11 to 26 would have become pregnant.
  • There does not seem to be a statistically different effect in efficacy between Day 1 and Day 4, but it does decline significantly by Day 5.[4] 
  • Women who are taking enzyme-inducing drugs (eg, phenytoin, rifampicin, etc) will be at risk of a higher failure rate. They should be advised that the IUCD is a more reliable method for them. If they choose to take LNG-EC, they should take 2 x 1.5 mg tablets as a single dose. This is outside the licence for the drug and they should be informed of this.[4]


  • Hypersensitivity to LNG.
  • Acute porphyria.
  • Severe liver disease.
  • Severe malabsorption syndromes (eg, Crohn's disease) might impair the efficacy of LNG-EC.
  • Rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption (preparations contain lactose).
  • Caution is recommended if there is a history of ectopic pregnancy. Previous ectopic pregnancy is not an absolute contra-indication.

NB: POEC can be safely used during lactation.


Reported side-effects include:

  • Nausea.
  • Vomiting.
  • Menstrual irregularities. Menses may be delayed, or there may be some spotting.
  • Dizziness.
  • Diarrhoea.
  • Breast tenderness.


  • Liver enzyme-inducing drugs. For example:
    • Anticonvulsants such as carbamazepine, oxcarbazepine, phenytoin, barbiturates, primidone, and topiramate.
    • Antibiotics - rifabutin and rifampicin (potent enzyme inducers).
    • St John's wort.
    • Antiretrovirals - particularly ritonavir-boosted protease inhibitors.
  • Ciclosporin. (LNG may increase the risk of toxicity by inhibiting metabolism of ciclosporin.)
  • Selegiline. (Avoid concomitant use. May cause toxicity.)
  • Tizanidine. (Monitor as may cause toxicity.)

Specific advice for women using LNG-EC

  • If vomiting occurs within two hours of taking LNG-EC, a repeat dose is needed.[4] 
  • Following use, women should be advised to use additional contraceptive precautions for seven days for the combined oral contraceptive pill (COCP), nine days for Qlaira®, and three days for the progestogen-only contraceptive pill (POCP).
  • If emergency contraception is used because of missed oral contraceptive pills, women should be advised to resume their normal pill-taking regime within 12 hours of taking LNG-EC.
  • There is no current evidence that POEC affects an existing pregnancy.[11][12]

This method has been available in the UK since October 2009, as ellaOne®. It is a second-generation SPRM (mifepristone is a first-generation SPRM) and is the only licensed oral choice for UPSI between 72 and 120 hours.

Mode of action[5][13] 

The main mechanism of action is by inhibition or delay of ovulation. A single dose in the mid-follicular phase has been shown to suppress the further development of follicles. If given around the time of the luteinising hormone (LH) surge, the rupture of follicles is inhibited. After the LH peak, it is not effective in delaying follicular rupture.


It consists of one tablet (30 mg) of UPA which should be taken as soon as possible after UPSI, but within 120 hours (five days) of the event.

Timing of use

It has been shown to be effective up to 120 hours after UPSI, or failure of the normal contraceptive method.


Pregnancy rates with UPA are around 0.9%-1.8% when taken within 120 hours.[1][9] - ie if 1,000 women had unprotected sex once, around 60 to 80 would become pregnant. If all those women had taken ellaOne®, only around 9 to 18 would have become pregnant.

There are data to show performance comparable to POEC and potentially more effective.[2] 

Efficacy may be reduced when the woman is taking liver enzyme-inducing medication, or medication which raises normal gastric pH.


Pregnancy or suspected pregnancy should be excluded before UPA is prescribed. There is insufficient research to advise safely on breast-feeding and it is therefore recommended that breast-feeding is best avoided for one week after a dose has been taken.

Severe liver disease or uncontrolled asthma are also contra-indications to its use.

Repeated use within the same menstrual cycle is contra-indicated.


Reported side effects include:

  • Vomiting. As with LNG, if a woman vomits within two hours of taking UPA, she should repeat the dose. If this is the case, consider an anti-emetic.
  • Nausea.
  • Dizziness.
  • Menstrual irregularities.
  • Abdominal pain.
  • Myalgia and back pain.
  • Pelvic pain.
  • Headache.
  • Mood disorders.


  • Medication which increases gastric pH - for example, antacids, proton pump inhibitors (PPIs), H2-receptor antagonists. They may reduce concentration of UPA and therefore reduce its efficacy.
  • Liver enzyme-inducing drugs. For example:
    • Anticonvulsants such as carbamazepine, oxcarbazepine, phenytoin, barbiturates, primidone, and topiramate.
    • Antibiotics - rifabutin and rifampicin (potent enzyme inducers).
    • St John's wort.
    • Antiretrovirals - particularly ritonavir-boosted protease inhibitors.
  • Contraceptives. UPA may compete with progestogens in contraceptive pills for progesterone receptors, and therefore reduce efficacy of ongoing contraception. Therefore, if starting or continuing oral contraception after using UPA, women should be advised to take additional contraceptive precautions:
    • For 14 days if on the COCP other than Qlaira®.
    • For 14 days if on the contraceptive ring or contraceptive patch.
    • For 14 days if using the progestogen-only implant or progestogen-only injection.
    • For 16 days if on Qlaira®.
    • For 9 days if on the POCP.
  • If quickstarting a new method of hormonal contraception after using UPA, do not start until 5 days later.

Mode of action 

  • It is thought that IUCDs have an inhibitory effect on both fertilisation and implantation.
  • Fertilisation inhibition occurs through direct toxicity effects of the copper on both ovum and sperm.
  • Copper can also have the effect of inhibiting sperm penetration of cervical mucus.
  • Inflammatory reaction effects on the endometrium due to the Cu-IUCD being in situ can also prevent implantation. If fertilisation has occurred, the mode of action is by preventing a fertilised egg implanting. Women should be aware of this, as some may have a moral view about this, although by law pregnancy begins at implantation, not at fertilisation. To ensure that an IUCD is inserted before the process of implantation begins, the IUCD should be fitted within the first five days (120 hours) following first UPSI in a cycle or within five days from the earliest estimated date of ovulation.
  • IUCDs containing at least 380 mm2 of copper are more effective than those containing less copper. 

Timing of use 

  • Can be used up to five days after UPSI.
  • If the timing of ovulation can be estimated, insertion can be beyond five days after UPSI, as long as insertion does not occur beyond five days from ovulation.
  • An IUCD should ideally be fitted at first presentation for EC. It may be appropriate to delay the insertion in certain circumstances - eg, until the next-day family planning clinic service is available. In such cases, POEC should be given in the interim.


  • Pregnancy rates are significantly less than 1% when the IUCD is used for EC - ie less than one woman in a hundred would become pregnant after a single episode of UPSI if the IUCD was used within five days.
  • It is the most effective form of EC, and the only one to provide ongoing protection if left in situ.[2] 


These are the same contra-indications as for insertion of a Cu-IUCD under other circumstances:

  • Puerperal sepsis and septic abortion.
  • Current PID.
  • History of copper allergy or Wilson's disease.
  • Markedly distorted uterine cavity.
  • Gestational trophoblastic disease with persistent elevated beta-hCG levels, or malignant disease.
  • Cervical or endometrial cancer.
  • Active infection with chlamydia or gonorrhoea.

Risk of PID 

  • There is a potential risk of PID when inserting an IUCD in a woman who has had UPSI.
  • It is recommended that, as a minimum, women at higher risk of STI (age ≤25 years, new sexual partner or ≥1 sexual partner in the previous year) should be offered testing for chlamydia.
  • For such high-risk women, the use of prophylactic antibiotics should also be considered when the IUCD is inserted.

Other points

  • Previous ectopic pregnancy is not a contra-indication to emergency IUCD use.
  • Non-copper-containing IUCDs (including the IUS) are not recommended for EC, as there is currently no available evidence of their effectiveness.
  • The IUCD may be removed following the next menstrual period if not required as long-term contraception.
  • It may also be removed if hormonal contraception is started within the first five days of the next cycle.
  • Discuss information about the failure rate, and document this.
  • Give a written advice sheet about EC.
  • Explain that their next period may be on time, early, or late.
  • Explain that they should return for a pregnancy test if they have not had a normal period within seven days of their expected next period or if they have irregular bleeding.
  • Advise that they should see a doctor immediately if they develop lower abdominal pain (consider the possibility of ectopic pregnancy).
  • Advise about a more definitive method of contraception for the future. Written information is helpful.
  • Discuss the risk of STI. They have all had unprotected sexual intercourse. They should be referred for a full sexual health screen as appropriate.
  • Examine and document Fraser-ruling competence if appropriate.[15]

Further reading & references

  • Halpern V, Raymond EG, Lopez LM; Repeated use of pre- and postcoital hormonal contraception for prevention of pregnancy. Cochrane Database Syst Rev. 2014 Sep 26;9:CD007595. doi: 10.1002/14651858.CD007595.pub3.
  1. Ulipristal Acetate (ellaOne®); Faculty of Sexual and Reproductive Healthcare New Product Review, 2009
  2. Cheng L, Che Y, Gulmezoglu AM; Interventions for emergency contraception. Cochrane Database Syst Rev. 2012 Aug 15;8:CD001324. doi: 10.1002/14651858.CD001324.pub4.
  3. Gemzell-Danielsson K, Rabe T, Cheng L; Emergency contraception. Gynecol Endocrinol. 2013 Mar;29 Suppl 1:1-14. doi: 10.3109/09513590.2013.774591.
  4. Emergency Contraception; Faculty of Sexual and Reproductive Healthcare (2011)
  5. Contraception - emergency; NICE CKS, November 2011 (UK access only)
  6. Emergency contraception; World Health Organization, July 2012
  7. Piaggio G, Kapp N, von Hertzen H; Effect on pregnancy rates of the delay in the administration of levonorgestrel for emergency contraception: a combined analysis of four WHO trials. Contraception. 2011 Jul;84(1):35-9. doi: 10.1016/j.contraception.2010.11.010. Epub 2011 Jan 7.
  8. Shohel M, Rahman MM, Zaman A, et al; A systematic review of effectiveness and safety of different regimens of levonorgestrel oral tablets for emergency contraception. BMC Womens Health. 2014 Apr 4;14:54. doi: 10.1186/1472-6874-14-54.
  9. 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, Volume 375, Issue 9714, Pages 555 - 562, 13 February 2010
  10. British National Formulary; NICE Evidence Services (UK access only)
  11. Summary of Product Characteristics (SPC) - Levonelle® 1500 micrograms; electronic Medicines Compendium, October 2014
  12. Summary of Product Characteristics (SPC) - Levonelle® One Step; electronic Medicines Compendium, October 2014
  13. Summary of Product Characteristics (SPC) - ellaOne® 30 mg; HRA Pharma UK Limited, electronic Medicines Compendium. March 2014
  14. UK Medical Eligibility Criteria for Contraceptive Use; Faculty of Sexual and Reproductive Healthcare (2009) (Revised May 2010)
  15. Contraceptive Choices for Young People; Faculty of Sexual and Reproductive Healthcare (2010)

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Dr Michelle Wright
Current Version:
Peer Reviewer:
Prof Cathy Jackson
Document ID:
448 (v6)
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