Emergency contraception
also: morning-after pill · levonorgestrel EC · ulipristal · EllaOne
Overview
Post-coital contraception. Copper IUD is most effective and the only method that works after ovulation; the oral options delay ovulation only.
Mechanism
Levonorgestrel and ulipristal delay/inhibit ovulation (ulipristal is a selective progesterone-receptor modulator effective even close to the LH surge). Neither works once ovulation has occurred — the Cu-IUD does (copper toxicity).
Indications
- Unprotected sex / contraceptive failure
The agents
double dose if BMI>26 or >70 kg
Less effective near ovulation; can restart hormonal contraception immediately.
Avoid breastfeeding 1 week; delay starting/restarting hormonal contraception 5 days; avoid in severe asthma on steroids.
most effective
Gold standard — also provides ongoing contraception.
Adverse effects
Repeat dose if vomiting within 2–3 h.
Cautions & contraindications
Progestogen reduces ulipristal efficacy — don't combine; delay contraception 5 days after ulipristal.
Interactions
- Enzyme inducers reduce oral EC efficacy → offer Cu-IUD or double-dose levonorgestrel
- Ulipristal ↔ progestogens mutually reduce efficacy
Monitoring & kinetics
Pregnancy test if period >7 days late
Sooner = better. Cu-IUD effective throughout the 120 h window regardless of cycle stage.
Source: FSRH — Emergency contraception