Emergency contraception — options and timing

Emergency contraception covers the time-sensitive options available after unprotected sex or contraceptive failure. What is most suitable depends on how much time has passed, where you are in your cycle, your usual contraception and any other medicines you take.

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What decides the outcome

Time since sex, cycle timing, usual contraception and other medicines determine the most suitable option for you. A licensed doctor reviews these factors case by case.

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Your path to treatment

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Who it is not suitable for

Because this is time-sensitive, the doctor’s assessment of timing, cycle stage and current contraception is what determines whether emergency contraception — and which option — is appropriate for you. Emergency pills do not protect against sexually transmitted infections, so this consultation does not replace STI testing or ongoing contraception planning.

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How Hi-Doctor handles it

An EU-licensed doctor reviews your questionnaire and, if appropriate, issues an electronic prescription valid across the EU. The medication, if the doctor prescribes it, is paid separately at the pharmacy at the price it sets — see pricing for the consultation fee. Hi-Doctor does not sell medications.

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Related reading

• Levonorgestrel — the emergency contraceptive pill and why timing matters
• Ulipristal acetate — the other emergency contraceptive option, with a longer window
• How a consultation works
• Safety and eligibility

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Mechanism of action

Both oral emergency contraceptives — levonorgestrel (LNG) and ulipristal acetate (UPA) — act primarily by delaying or inhibiting ovulation, but their pharmacological windows differ (PMID 25117156). LNG is a synthetic progestogen that suppresses the luteinising hormone (LH) surge by binding the progesterone receptor in the hypothalamic–pituitary axis. It is effective only when taken before the LH surge has begun; once the surge is underway, LNG cannot prevent follicular rupture. This limits its window to the follicular phase, before ovulation. UPA is a selective progesterone receptor modulator (SPRM) that binds the progesterone receptor with higher affinity than LNG and can inhibit or delay follicular rupture even after the LH surge has started, giving it a wider therapeutic window of up to 120 hours after unprotected intercourse. In head-to-head trials, UPA maintained lower pregnancy rates than LNG at every time interval within that window. Importantly, neither LNG nor UPA has been shown to impair endometrial receptivity or prevent implantation of a fertilised ovum in vivo. Their efficacy depends wholly on interfering with ovulation; once fertilisation has occurred, they do not interrupt an established pregnancy. The copper intrauterine device (IUD) remains the most effective emergency contraceptive across all cycle stages and provides ongoing contraception once inserted. The doctor’s assessment of cycle timing — specifically, whether the woman is in the pre-ovulatory, peri-ovulatory, or post-ovulatory phase — determines which oral option, if any, is likely to be effective, or whether the copper IUD is the more appropriate recommendation.

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Population considerations

Body weight affects the efficacy of oral emergency contraceptives. Levonorgestrel appears less effective in women with a body mass index (BMI) above 25 kg/m², and ulipristal acetate may have reduced efficacy above a BMI of 30 kg/m², though the evidence is not consistent enough for a strict BMI cut-off in all guidelines. The copper IUD remains fully effective regardless of body weight, which is an important consideration in the doctor’s assessment. Ulipristal acetate is metabolised by CYP3A4; concomitant use of strong CYP3A4 inducers — rifampicin, certain antiepileptics (phenytoin, carbamazepine), St John’s Wort — can reduce its plasma concentration and potentially diminish contraceptive effect. Where such interactions are identified, the reviewing doctor may recommend the copper IUD instead.

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Copper IUD as emergency contraception

The copper intrauterine device is the most effective emergency contraceptive, with a failure rate below one per thousand when inserted within 5 days of unprotected intercourse (PMID 31686919). Copper ions released from the device are toxic to spermatozoa and impair their motility and capacitation, preventing fertilisation. The device also produces a local endometrial inflammatory reaction that is hostile to sperm survival. Unlike oral methods, the copper IUD provides ongoing contraception as long as it remains in place, and its efficacy is unaffected by cycle stage or body weight. The doctor considers whether the woman is a candidate for IUD insertion based on her history, and refers her to a clinician who can insert it if that is the most appropriate option.

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