• Type: Contraceptive
  • Dosage Forms: Tablet 0.75mg, 1.5mg
  • Routes of Administration: oral, intrauterine (IUD)
  • Common Trade Names: Plan-B, most brands of combination OCPs, Mirena

Adult Dosing

  • Emergency contraception: 0.75mg PO q12 x 2 OR 1.5mg PO once, as soon as possible within 72 hours of unprotected sex

Pediatric Dosing

  • See above

Special Populations


  • Allergy to class/drug
  • Pregnancy
  • IUDs only:
    • Active pelvic infection or STD
    • Immunocompromise
    • Known or suspected breast, uterine, or cervical cancer
    • Acute liver disease or liver tumor
    • Structural uterine anomaly including fibroids that distort uterine cavity

Adverse Reactions


  • Pills:
    • DVT/PE, stroke, MI
    • Depression, suicidality
  • IUDs:
    • Ectopic pregnancy
    • Uterine perforation
    • PID, sepsis


  • Nausea, abdominal pain
  • Headache, dizziness
  • Abnormal vaginal bleeding, breast tenderness, ovarian cysts
  • Pills:
    • Acne
    • Fatigue
  • IUDs:
    • Pelvic pain, vulvovaginitis
    • Irregular menses, hypomenorrhea/amenorrhea


  • Half-life: Oral: 17-27.5h
  • Metabolism: Hepatic, primarily via CYP3A4
  • Excretion: Renal, fecal

Mechanism of Action

  • Progestogen; inhibits ovulation or fertilization by altering tubal transport of sperm and/or ova


See Also