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.
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.
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.
Key medicines
Ulipristal acetate emergency contraceptionTake 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.
Levonorgestrel emergency contraceptionTake 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.