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Emergency Contraceptive (Progestogen) Pregnancy: Not indicated in pregnancy. If taken without knowing pregnancy — no evidence of teratogenicity or harm to established pregnancy.

Levonorgestrel (Emergency Contraception)

Brand names: Levonelle 1500, Upostelle, Ezinelle

Adult dose

Dose: 1500 micrograms (1.5mg) as a single oral dose
Route: Oral
Frequency: Single dose — as soon as possible after unprotected sex
Max: 1500 micrograms single dose
Efficacy: most effective within 12h of unprotected sex (95%), reduces to ~85% at 12–24h, ~58% at 48–72h; not recommended beyond 72h (use copper IUD up to 120h or ulipristal 30mg up to 120h). Mechanism: delays or inhibits ovulation; does not disrupt established implantation. Available OTC without prescription. Can be used more than once in a menstrual cycle if needed. Women >70kg or BMI >26: consider double dose (3mg) or copper IUD — reduced efficacy at higher weight (FSRH guidance).

Paediatric dose

Route: Oral
Frequency: Single dose
Max: 1.5mg
Licensed for use in adolescents post-menarche — same dose as adult. Available without age restriction in UK pharmacies. Counsel on ongoing contraception post-emergency contraception.

Dose adjustments

Renal

No dose adjustment required.

Hepatic

Hepatic impairment: use with caution; severe hepatic disease — consider copper IUD instead.

Clinical pearls

  • Copper IUD is the most effective emergency contraception (>99% effective up to 120h) — offer as first-line if <120h; can remain in situ as ongoing contraception
  • Weight/BMI: FSRH recommends double dose (3mg) or copper IUD in women ≥70kg due to reduced levonorgestrel exposure — pharmacokinetic evidence
  • After levonorgestrel: advise starting regular contraception immediately; if starting COCP or POP same day, barrier method needed for 7–9 days
  • Ulipristal (EllaOne 30mg) is more effective than levonorgestrel at 72–120h — preferred for later presentations

Contraindications

  • Severe hepatic impairment
  • Hypersensitivity to levonorgestrel
  • Note: NOT contraindicated in most conditions where regular progestogens are cautioned — short single dose

Side effects

  • Nausea and vomiting (if vomiting within 3h of dose — repeat dose or use alternative)
  • Irregular bleeding (next period may be early or late)
  • Headache
  • Breast tenderness
  • Dizziness

Interactions

  • Enzyme-inducing drugs (rifampicin, carbamazepine, phenytoin, St John's Wort) — significantly reduce efficacy: use copper IUD instead or double dose (3mg) if IUD refused
  • Ulipristal acetate — do not use levonorgestrel within 5 days before or after ulipristal (mutual antagonism)

Monitoring

  • Pregnancy test if next period >7 days late or abnormally light
  • STI screening if applicable
  • Review ongoing contraception needs

Reference: BNFc; BNF 90; FSRH Emergency Contraception Guideline 2017 (updated 2023); NICE. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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