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Textbook/Sexual and reproductive health/Emergency contraception
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Emergency contraception

Select copper IUD, ulipristal or levonorgestrel emergency contraception by intercourse and ovulation timing, interactions, weight and the ongoing-method plan.

29 min full readUK scopeSources checked 13 Sept 2026Clinical review pending
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Recent unprotected intercourse, sexual assault or method failure requires same-day assessment because oral and intrauterine options have finite windows.

Action: Record every exposure in the cycle, last normal period, current contraception and enzyme-inducing medicines; offer copper IUD first when eligible, provide oral EC immediately if chosen and complete the ongoing contraception and testing plan.

Open the sections you need. The overview is shown first.
01Purpose and principlesWhat the treatment does and how it fits into care.

The copper IUD prevents fertilisation and remains effective when oral methods can no longer delay ovulation. It is therefore the most effective EC across weight and interaction contexts. Eligibility requires pregnancy exclusion and procedural assessment, but service delay should not be created by unnecessary screening or routine antibiotics.

UPA is a selective progesterone-receptor modulator with activity up to 120 hours. LNG is recommended within 72 hours and loses effectiveness with delay. Both work mainly by postponing ovulation, so neither treats an implanted pregnancy. Their exposure can be reduced by enzyme-inducing drugs; current progestogen can oppose UPA’s action.

The consultation is incomplete until ongoing contraception is protected. Hormonal methods can begin immediately after LNG. After UPA, starting progestogen within five days can counter its effect, so wait and use condoms or abstinence, then complete the normal backup interval for the chosen method. Test 21 days after the most recent risk.

Key points

  • Offer a copper IUD to every eligible EC user because it is the most effective method, works after ovulation and can remain for continuing contraception.
  • Insert copper IUD within 120 hours of the first unprotected intercourse in the cycle or, when ovulation can be estimated, within five days after the earliest likely ovulation date.
  • Use ulipristal acetate 30mg within 120 hours or levonorgestrel 1.5mg within 72 hours. Oral EC delays ovulation and is ineffective after ovulation has occurred.
  • Current or recent enzyme induction makes UPA unsuitable and may reduce LNG: offer copper IUD, or if declined give LNG 3mg once and explain that effectiveness is uncertain.
  • After LNG quick-start contraception immediately with method-specific backup. After UPA delay hormonal contraception five days, then add the full method-specific backup interval.
  • A single EC dose protects only sex that has already occurred; further unprotected sex can create a new pregnancy risk, so provide condoms, ongoing contraception and clear repeat-EC advice.
  • Arrange a pregnancy test 21 days after the latest unprotected sex, and assess earlier for a late or abnormal period, pregnancy symptoms or pelvic pain.
  • No interruption of breastfeeding is required after a single LNG or UPA EC dose under the January 2025 CoSRH statement.
02Indications, selection and cautionsWho may benefit, who needs urgent treatment and important alternatives.
Condom or method failureRed flag

Breakage, expulsion, delayed injection, missed pills or extended hormone-free interval require method-specific risk assessment.

Ovulation timing

Cycle length and last menstrual period estimate the earliest ovulation date, but variability makes copper IUD preferable when uncertainty matters.

Enzyme-inducer exposureRed flag

Current use or the 28 days after stopping changes oral EC choice and dose.

Possible established pregnancyRed flag

Late period, pregnancy symptoms, pain or bleeding requires testing and ectopic assessment; EC will not end a pregnancy.

Further-sex risk

Oral EC does not provide continuing protection, making immediate counselling and the restart schedule essential.

Red flags requiring action

  • Pelvic pain, collapse, shoulder-tip pain or bleeding with a late period requires urgent ectopic-pregnancy assessment rather than routine EC alone.
  • A copper IUD is the most effective EC and can be inserted within 120 hours after first unprotected sex in the cycle or within five days of earliest estimated ovulation.
  • Levonorgestrel 1.5mg is recommended as soon as possible within 72 hours; ulipristal 30mg can be used up to 120 hours and is generally the more effective oral option later in the window.
  • During enzyme induction and for 28 days after stopping, offer copper IUD; if declined or unsuitable use LNG 3mg once with uncertainty counselling and do not use UPA.
  • After UPA wait five days before any progestogen-containing contraception; after LNG, ongoing hormonal contraception can start immediately.
03Assessment before treatmentTests and checks that guide safe selection.
Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

  1. 01
    Dated sexual and cycle historyFirst step
    Why
    Identify the first and latest unprotected sex, cycle day and possible ovulation window.
    Interpretation and limitations
    Use the first exposure for the 120-hour copper-IUD rule and the earliest estimated ovulation when applying the alternative window.
  2. 02
    Pregnancy test
    Why
    Detect an established pregnancy when the period is late or timing is uncertain.
    Interpretation and limitations
    A negative result before 21 days from latest sex cannot exclude a new pregnancy and requires repeat testing.
  3. 03
    Contraceptive-error review
    Why
    Determine whether missed pills, patch, ring, injection, implant or IUD failure creates an EC indication.
    Interpretation and limitations
    Each method has its own threshold; do not apply one generic late rule.
  4. 04
    Medicine and weight assessment
    Why
    Identify enzyme induction and factors that may reduce oral EC effectiveness.
    Interpretation and limitations
    Copper IUD remains preferred; higher weight or BMI can strengthen the case for UPA or double-dose LNG, but double-dose UPA is not supported.
04Treatment approachPreparation, options, escalation and aftercare.
01EC choice pathwayOffer copper before comparing tabletsFirst stepUnprotected sex or method failure falls within an emergency-contraception window.
  1. 1Exclude urgent pregnancy symptoms, date every exposure, estimate earliest ovulation and identify current hormones and enzyme induction.
  2. 2Offer copper IUD as most effective within 120 hours of first exposure or five days after earliest estimated ovulation.
  3. 3If oral EC is chosen, select UPA or LNG by timing, recent progestogen, inducer use, weight and the restart plan.
02After UPA pathwayProtect the ovulation delayOral ulipristal 30mg emergency contraception has been given.
  1. 1Wait five full days before starting or restarting any progestogen-containing contraception.
  2. 2Use condoms or abstain during the wait and then for the complete backup period required by the restarted method.
  3. 3Test 21 days after the latest unprotected sex and return sooner for pain, bleeding or pregnancy symptoms.
03Inducer pathwayUse an unaffected EC methodAn enzyme-inducing medicine is being used or stopped within the previous 28 days.
  1. 1Offer copper IUD because hepatic induction does not reduce its emergency effect.
  2. 2If declined or unsuitable, give LNG 3mg once as soon as possible and explain the evidence uncertainty.
  3. 3Do not use UPA and arrange ongoing contraception unaffected by induction plus follow-up testing.
05Regimens, contraindications and interactionsTreatment details and the circumstances that modify them.
Delays ovulation later in the fertile window than levonorgestrel and is generally the more effective oral EC.

Ulipristal acetate emergency contraception

Take 30mg orally once as soon as possible and within 120 hours of unprotected intercourse.

Do not use with current or recent enzyme induction; recent progestogen may reduce effect, wait five days before restarting hormones, and do not double the dose.

Delays ovulation and allows immediate start or restart of ongoing hormonal contraception.

Levonorgestrel emergency contraception

Take 1.5mg orally once as soon as possible and within 72 hours; use 3mg once when an enzyme inducer is current or was stopped within 28 days and copper IUD is declined.

Effectiveness falls with delay and after ovulation; higher weight and induction may reduce effect, so offer copper IUD and arrange follow-up testing.

06Complications, monitoring and follow-upAdverse effects, response and longer-term review.
  • Confirm that the chosen ongoing method starts at the correct time and that backup lasts for the complete method-specific interval.
  • Arrange pregnancy testing 21 days after the latest unprotected sex, not simply 21 days after the clinic visit.
  • Advise urgent assessment for unilateral pain, collapse, shoulder-tip pain or abnormal bleeding.
  • Review repeat EC use, safeguarding, STI testing and a sustainable contraception choice without judgement.
07Special situationsVariants, exceptions and circumstances that change the usual approach.

Copper works after ovulation

Its post-fertilisation-independent contraceptive action preserves efficacy when oral ovulation delay is too late.

First and latest exposures differ

The first exposure defines one copper-IUD window, while the latest exposure dates the pregnancy test.

UPA needs hormone separation

Five days without progestogen protects ulipristal action before the ongoing method is restarted.

Induction outlasts the tablets

The EC interaction continues for 28 days after an enzyme-inducing medicine is stopped.

08Common pitfallsFrequent interpretation and management errors.
  1. 01

    Offering only a morning-after pill without copper IUD counselling.

  2. 02

    Using standard LNG or any UPA during enzyme induction.

  3. 03

    Restarting POP immediately after UPA.

  4. 04

    Assuming one EC dose protects subsequent intercourse.

  5. 05

    Omitting a 21-day pregnancy test and ectopic safety net.

Practice

Two practice questions

Question 1 of 20 correct
Sexual and reproductive healthOriginal SBA

Offer the most effective EC

A patient presents 96 hours after unprotected intercourse and wants the most effective emergency contraception with ongoing protection. Pregnancy can reasonably be excluded. What should be offered first?

Sources and review status3 sources · checked 13 Sept 2026 · clinical review pending
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 13 Sept 2026; clinical approval remains outstanding.

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom