Skip to content
ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
Selective Progesterone Receptor Modulator (SPRM)

Ulipristal Acetate

Brand names: Esmya (fibroids), EllaOne (emergency contraception)

Ulipristal acetate is a selective progesterone-receptor modulator used as emergency contraception, effective when taken up to 120 hours (5 days) after unprotected sex. It may be more effective than levonorgestrel, particularly later in the cycle.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It modulates the progesterone receptor to delay or inhibit ovulation, including when taken close to the time of ovulation; it is not an abortifacient.

Prescribing in practice

  • Starting or restarting hormonal (progestogen) contraception immediately afterwards reduces its effectiveness, so wait the recommended interval before doing so.
  • Avoid in severe asthma that is inadequately controlled by oral corticosteroids.
  • Enzyme-inducing drugs reduce its effectiveness, in which case a copper intrauterine device is preferred.

Monitoring

No routine monitoring is required; advise a pregnancy test if the next period is late or unusually light, and arrange ongoing contraception after the recommended interval.

Counselling the patient

  • Take it as soon as possible after unprotected sex, up to five days afterwards.
  • Do not start or restart hormonal contraception straight away; use condoms or abstain until your prescriber advises it is time, then continue reliable contraception.
  • If you vomit within a few hours of the dose, seek advice as you may need to repeat it.

Evidence & guidelines

Recommended emergency contraceptive option (FSRH; NICE CKS).

Reference: MHRA Drug Safety Update (2020) — Esmya liver injury; PEARL trials I-IV (Donnez et al. NEJM 2012); NICE TA519; SPC Esmya; SPC EllaOne; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

Calculators