01Purpose and principlesWhat the treatment does and how it fits into care.
Emergency contraception prevents pregnancy after unprotected intercourse or contraceptive compromise; it does not disrupt an established pregnancy. Ask about every episode of intercourse in the current cycle, first day of the last normal period, shortest usual cycle, current or missed method, childbirth or pregnancy end, weight and BMI, medicines, breastfeeding, medical history and pregnancy symptoms. Do not refuse care because the patient presents repeatedly or cannot identify a precise ovulation day.
The copper IUD is the first-line and most effective emergency option. It can be inserted within five days after the first unprotected intercourse in the natural cycle, or within five days after the earliest likely ovulation when ovulation can be estimated and this permits later insertion. It remains effective after ovulation, unlike oral agents, and provides ongoing contraception immediately. Discuss insertion, bleeding, pain, perforation, expulsion and infection risk and offer oral EC promptly if same-day insertion is unavailable or declined.
Ulipristal acetate 30 mg is a selective progesterone-receptor modulator licensed to 120 hours. It delays ovulation when the luteinising hormone surge has begun earlier than levonorgestrel can, although neither oral agent is effective after ovulation. It is usually the better oral choice from 72 to 120 hours and when intercourse may have occurred near ovulation. Do not use with current or recent enzyme induction, and avoid in severe asthma treated with oral glucocorticoids.
Levonorgestrel 1.5 mg should be taken as soon as possible and is licensed within 72 hours. It is less effective close to ovulation and evidence beyond 72 hours is weaker; a copper IUD or ulipristal is generally preferable when time allows. If vomiting occurs within three hours of either oral dose, repeat the dose. A second oral dose may be given after further unprotected intercourse in the same cycle according to current guidance, but repeated rescue is not a substitute for an ongoing method.
Higher body weight may reduce oral effectiveness, more clearly for levonorgestrel. Above 70 kg or BMI 26 kg/m², offer copper-IUD EC first; if it is declined, consider ulipristal or LNG 3 mg while explaining that doubling has not been shown to restore effectiveness. Above 85 kg or BMI 30 kg/m², ulipristal may also be less effective and it is unknown whether it or double-dose LNG is superior. Do not double ulipristal.
Hepatic enzyme inducers accelerate oral EC metabolism. If an inducer has been used in the preceding 28 days, offer a copper IUD. If it is unsuitable or declined, ulipristal is not recommended and double-dose levonorgestrel 3 mg may be considered with explicit uncertainty. Enzyme induction does not reduce copper-IUD effectiveness. Examples include rifampicin, rifabutin, carbamazepine, phenytoin, phenobarbital, primidone, oxcarbazepine, topiramate and St John’s wort.
Starting ongoing contraception differs after the two oral medicines. After levonorgestrel, quick-start an eligible hormonal method immediately, then use additional precautions for the method’s specified interval. After ulipristal, wait five days before any progestogen-containing method because progestogen can reduce ulipristal’s ovulation-delaying effect; use condoms or abstain during the wait and then for the new method’s onset period. A copper IUD is immediately effective.
Finish with follow-up. Explain that oral EC covers prior intercourse only, give written return precautions and perform a pregnancy test 21 days after the latest unprotected intercourse, even if bleeding occurs atypically. Test sooner if the next period is more than seven days late, unusually light or accompanied by pregnancy symptoms. Pain, bleeding, syncope or a positive test requires pregnancy-location assessment. Offer STI testing and assault support according to exposure.
Key points
- Offer emergency contraception after unprotected intercourse on any day of a natural cycle because ovulation timing varies and pregnancy is possible outside predicted fertile days.
- The copper IUD is the gold-standard emergency method and should be offered first: it is the most effective and provides immediate ongoing contraception.
- Insert a copper IUD within five days of the first unprotected intercourse in the cycle or within five days of earliest estimated ovulation when that timing can be established.
- Ulipristal acetate 30 mg is licensed within 120 hours and is generally the preferred oral option near ovulation or 72–120 hours after intercourse when a copper IUD is not used.
- Levonorgestrel 1.5 mg is licensed within 72 hours; give it as soon as possible and prefer a copper IUD or ulipristal where declining efficacy makes LNG less suitable.
- Weight and BMI may reduce oral EC effectiveness: above 70 kg or BMI 26 kg/m² consider ulipristal or LNG 3 mg if no copper IUD; above 85 kg or BMI 30 kg/m² neither oral option is known to be superior.
- After ulipristal, wait five days before starting a progestogen-containing method; after levonorgestrel, start suitable ongoing hormonal contraception immediately.
- Oral EC does not protect later intercourse. Give method-specific condoms or abstinence advice and arrange a pregnancy test 21 days after the latest unprotected intercourse.
- Breastfeeding does not need to be interrupted after a single ulipristal 30 mg dose under the current CoSRH statement; avoid repeating obsolete advice to express and discard milk for one week.
02Indications, selection and cautionsWho may benefit, who needs urgent treatment and important alternatives.
Intercourse near the predicted fertile window reduces oral options because levonorgestrel loses effect earlier in the ovulatory process and neither pill works after ovulation.
Rifamycins, several antiseizure medicines and St John’s wort can lower oral emergency-contraception exposure for 28 days after stopping.
A patient who takes oral EC and then has unprotected sex later in the cycle has a new pregnancy risk requiring reassessment.
A period more than seven days late, unusually light bleeding, pregnancy symptoms or pain warrants testing and, when positive, location assessment.
Emergency contraception becomes relevant from day 21 after childbirth unless all strict lactational-amenorrhoea criteria are met; a copper IUD is used from day 28.
03Assessment before treatmentTests and checks that guide safe selection.
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.
- 01
Intercourse and cycle chronologyFirst step - Why
- Identify copper-IUD eligibility, oral timing and whether ovulation may already have occurred.
- Interpretation and limitations
- Record the first and every subsequent exposure, last normal period and shortest cycle; predictions are estimates and should not be used to deny EC.
- 02
Pregnancy test - Why
- Detect an existing pregnancy when periods are late or symptoms suggest it and provide a baseline when uncertainty exists.
- Interpretation and limitations
- A negative test cannot exclude conception from recent intercourse. Repeat 21 days after the latest unprotected intercourse regardless of EC choice.
- 03
Weight and body mass index - Why
- Inform oral EC counselling and choice where reduced effectiveness is possible.
- Interpretation and limitations
- Above 70 kg or BMI 26 kg/m² consider UPA or LNG 3 mg after Cu-IUD discussion; above 85 kg or BMI 30 kg/m² neither oral choice is known to be superior.
- 04
Complete medicine history - Why
- Identify enzyme induction and medicines that alter ulipristal suitability or ongoing contraception.
- Interpretation and limitations
- Include herbal products and the preceding 28 days. Prefer copper IUD with an inducer; do not use ulipristal and consider LNG 3 mg only if needed.
- 05
Targeted sexual-health assessment - Why
- Address STI, HIV and safeguarding risk associated with the same exposure.
- Interpretation and limitations
- Testing sites and windows follow the sexual history. HIV PEP and forensic care are time-critical and proceed alongside EC, not after it.
04Treatment approachPreparation, options, escalation and aftercare.
01Gold standardOffer copper-IUD emergency contraceptionFirst stepGold standardThe patient presents within a recognised post-intercourse or post-ovulation insertion window.+
- 1Take a rapid eligibility, pregnancy, infection and consent history and explain that the copper IUD is the most effective option and gives immediate ongoing protection.
- 2Arrange same-day insertion whenever possible using the five-day intercourse or earliest-ovulation rule, with analgesia, procedural consent and safety-netting.
- 3If insertion cannot occur immediately, give an appropriate oral agent without avoidable delay and retain the planned copper-IUD pathway when still within time.
02Oral choiceMatch drug to timing and modifiersA copper IUD is declined, contraindicated or inaccessible within the valid window.+
- 1Use ulipristal 30 mg within 120 hours when it offers the better oral profile, checking severe steroid-treated asthma, progestogen exposure and enzyme induction.
- 2Use levonorgestrel 1.5 mg as soon as possible within its licensed window when appropriate, and apply current weight or BMI and enzyme-inducer dose guidance.
- 3Repeat the dose if vomiting occurs within three hours and reassess any later unprotected intercourse as a new event.
03Ongoing coverPrevent a second exposureOral emergency contraception has been supplied and pregnancy is not desired.+
- 1After levonorgestrel, quick-start an eligible hormonal method immediately; after ulipristal, defer progestogen-containing contraception for five complete days.
- 2Specify condoms or abstinence during the waiting and onset periods and explain that oral EC gives no protection from later intercourse.
- 3Arrange a pregnancy test 21 days after the latest unprotected intercourse and urgent assessment for pain, collapse, abnormal bleeding or a positive result.
04Enzyme inductionPrefer the unaffected methodAn enzyme inducer is current or was stopped within the previous 28 days.+
- 1Offer copper-IUD EC and explain that its effectiveness is not reduced by hepatic enzyme induction.
- 2If it is declined or unsuitable, avoid ulipristal and consider levonorgestrel 3 mg while being explicit that effectiveness data are limited.
- 3Arrange an ongoing IUD or DMPA method unaffected by induction and ensure the interacting medicine and teratogenic risk are reviewed.
05Regimens, contraindications and interactionsTreatment details and the circumstances that modify them.
Ulipristal acetate emergency contraception
Take 30 mg orally once as soon as possible and no later than 120 hours after unprotected intercourse; repeat once if vomiting occurs within three hours.Do not use with enzyme induction in the preceding 28 days or severe asthma treated with oral glucocorticoids; wait five days before progestogen contraception and do not double for weight.
Levonorgestrel emergency contraception
Take 1.5 mg orally once as soon as possible within 72 hours; repeat if vomiting occurs within three hours. Consider 3 mg under current weight or enzyme-inducer guidance when no copper IUD is used.Effectiveness falls with delay and near ovulation and may be lower at higher weight; a doubled dose has uncertain efficacy and oral treatment does not protect later intercourse.
06Complications, monitoring and follow-upAdverse effects, response and longer-term review.
- Confirm that ongoing contraception actually started, including the five-day progestogen delay after ulipristal and the full additional-precaution interval afterwards.
- Arrange and document a urine pregnancy test 21 days after the latest unprotected intercourse, not merely 21 days after the EC consultation.
- Reassess immediately after any further unprotected intercourse because the earlier oral dose does not protect the remainder of the cycle.
- Escalate a positive test, pain, bleeding, dizziness or collapse for pregnancy-location assessment and record whether an IUD is in situ.
- Complete STI testing, vaccination, HIV PEP follow-up, forensic referral and safeguarding actions according to the exposure and patient’s choices.
07Special situationsVariants, exceptions and circumstances that change the usual approach.
Copper works after ovulation
This distinguishes it from oral agents and explains why an IUD remains the most effective emergency method when ovulation timing is close or uncertain.
Ulipristal and progestogen compete
Starting a progestogen too soon can undermine ulipristal’s receptor-mediated ovulation delay, so the five-day wait is clinically meaningful.
The dose is not future cover
Oral EC addresses intercourse that has already occurred; subsequent sex creates a new risk until the ongoing method becomes effective.
Double LNG carries uncertainty
Guideline-recommended consideration at higher weight or with enzyme induction does not prove that 3 mg restores standard effectiveness.
A test closes the loop
Bleeding after EC may be early, late or irregular, making a correctly timed 21-day pregnancy test more reliable than cycle appearance alone.
08Common pitfallsFrequent interpretation and management errors.
- 01
Offering an oral pill without explaining that the copper IUD is the most effective emergency option.
- 02
Refusing emergency contraception because intercourse occurred on a supposedly safe cycle day.
- 03
Quick-starting a progestogen-containing method immediately after ulipristal instead of waiting five days.
- 04
Using standard-dose oral EC with an enzyme inducer or doubling ulipristal without evidence.
- 05
Assuming oral EC protects subsequent intercourse in the same cycle.
- 06
Failing to arrange a pregnancy test 21 days after the latest risk or address STI and assault needs.