Synopsis
Select the most effective emergency contraception from intercourse and ovulation timing, weight, enzyme-inducing medicines and ongoing-method plans, then prevent further risk in the same cycle.
- 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.
Key red flags
Pelvic or abdominal pain, bleeding, dizziness, shoulder-tip pain or collapse with a positive or uncertain pregnancy test needs urgent ectopic-pregnancy assessment.
Non-consensual sex requires trauma-informed care for injury, forensic choices, STI prevention, HIV PEP, hepatitis vaccination and safeguarding alongside emergency contraception.
Severe asthma controlled with oral glucocorticoids makes ulipristal acetate unsuitable because of an important pharmacodynamic concern; select another emergency method.
Current or recent hepatic enzyme induction can make both standard levonorgestrel and ulipristal unreliable, making copper-IUD access particularly important.
Investigation priorities
Identify copper-IUD eligibility, oral timing and whether ovulation may already have occurred.
Management branches
The patient presents within a recognised post-intercourse or post-ovulation insertion window.
- Take a rapid eligibility, pregnancy, infection and consent history and explain that the copper IUD is the most effective option and gives immediate ongoing protection.
- Arrange same-day insertion whenever possible using the five-day intercourse or earliest-ovulation rule, with analgesia, procedural consent and safety-netting.
- If insertion cannot occur immediately, give an appropriate oral agent without avoidable delay and retain the planned copper-IUD pathway when still within time.