Unprotected Sex and Emergency Contraception (EC)
Related Subjects:
| Management of Unprotected Sex and Emergency Contraception (EC)
| Contraception request/advice
| Combined Oral contraceptive pill (COCP)
⚠️ Emergency contraception (EC) & post-exposure care helps reduce the risks after unprotected sex or contraceptive failure.
⏱️ Timing matters: EC and HIV PEP work best when started early.
🛡️ EC prevents pregnancy - it does not protect against STIs.
1️⃣ Rapid risk assessment (what you must check first)
- ⏰ Time since sex: determines which EC/PEP options are still effective.
- 🩸 Pregnancy risk: last menstrual period (LMP), usual cycle length, likely ovulation window, current contraception, any missed pills/late injection.
- 🧬 STI/HIV risk: partner risk factors, known HIV status, condom failure, exposure type.
- 🚨 Safeguarding: sexual assault, coercion, under-18s, or inability to consent → urgent specialist pathway.
2️⃣ Emergency contraception options (UK)
| Method |
Time window |
Key points |
| 💊 Levonorgestrel (LNG) |
Best ≤72 hours (3 days) |
Works mainly by delaying ovulation (less useful if ovulation already occurred).
Can be used when quick access is needed.
|
| 💊 Ulipristal acetate (UPA) |
≤120 hours (5 days) |
Often more effective later in the window than LNG.
Interacts with ongoing hormonal contraception (see follow-on advice below).
|
| ⚙️ Copper IUD (Cu-IUD) |
≤5 days after sex (sometimes later depending on cycle/ovulation timing) |
Most effective EC and provides ongoing contraception once fitted.
Useful if higher pregnancy risk or EC pills may be less effective.
|
🧠 Mechanism in one line: LNG/UPA mainly delay ovulation; the Cu-IUD creates a copper-mediated environment that prevents fertilisation (and is the most effective EC option).
3️⃣ Choosing the best EC (practical)
- ⭐ Most effective overall: choose a Cu-IUD when feasible, especially if risk is high or timing is late. (CKS notes very low pregnancy rates with Cu-IUD.)
- 📆 If within 5 days: UPA or Cu-IUD remain options; LNG is best within 72 hours.
- ⚖️ Higher weight/BMI: EC pills may be less effective; consider Cu-IUD first, or follow local FSRH-based guidance (some settings advise higher LNG dose in higher BMI/weight).
- 💊 Enzyme-inducing drugs (e.g., some antiepileptics, rifampicin/rifabutin, St John’s wort): prefer a Cu-IUD because EC pills can be less reliable.
4️⃣ What to do after EC (common pitfalls)
- 🩸 Bleeding changes are common: spotting or an early/late period can happen.
- 🧪 Pregnancy test: if the next period is >7 days late or unusually light/painful, do a test and assess for ectopic symptoms.
- 🤢 Vomiting: if vomiting soon after EC, seek advice about repeating the dose (timing depends on the product).
- 🛡️ Ongoing contraception:
- After LNG: hormonal contraception can usually be started/continued straight away (plus condoms until effective).
- After UPA: delay starting hormonal contraception for several days (commonly 5 days in UK guidance) and use condoms until the method is effective.
5️⃣ HIV post-exposure prophylaxis (PEP)
- ⏱️ When? Start as soon as possible and generally within 72 hours of a significant exposure.
- 💊 Course: typically 28 days of combination antiretrovirals (local regimens vary; specialist/sexual health services usually guide this).
- 🧪 Baseline tests: HIV test, renal/liver function, hepatitis serology, pregnancy test where relevant.
- 📆 Follow-up testing: schedule depends on the clinic and assay used (commonly includes testing at baseline and again weeks later; follow local sexual health protocol).
- 🤝 Adherence matters: missed doses reduce effectiveness - manage nausea/headache proactively and arrange support.
6️⃣ Other STI prevention, testing, and vaccines
- 🧪 Offer STI testing based on exposure risk (commonly includes chlamydia, gonorrhoea, syphilis, HIV; hepatitis testing where indicated).
- 💉 Hepatitis B: if not immune, offer vaccination; add specialist advice if exposure is high risk.
- 🔁 Repeat tests: some infections require repeat testing after the window period (services will provide a timetable).
7️⃣ Safety-net and red flags 🚨
- Severe lower abdominal pain, shoulder tip pain, collapse, or heavy bleeding → consider ectopic pregnancy and seek urgent care.
- Genital ulcers, severe dysuria, fever, pelvic pain, or systemic symptoms → urgent assessment for STI complications.
- Any concern about assault, coercion, or safeguarding → urgent specialist pathway.
📚 References (UK)
