What is the best method of emergency contraception?

Best Method of Emergency Contraception

The copper intrauterine device (Cu-IUD) is the single most effective emergency contraceptive method and should be your first choice when feasible, followed by ulipristal acetate (30 mg) as the best oral option, particularly beyond 72 hours or in women with higher BMI. 1, 2

Effectiveness Hierarchy

The evidence clearly establishes a tiered effectiveness ranking:

• Cu-IUD: Most effective emergency contraceptive available, can be inserted within 5 days of unprotected intercourse (or up to 5 days after ovulation if timing can be estimated), and provides ongoing contraception 1, 2

• Ulipristal acetate (UPA, 30 mg): Second most effective option, maintains consistent efficacy throughout the full 120-hour (5-day) window after unprotected intercourse 1, 2, 3

• Levonorgestrel (1.5 mg): Third in effectiveness, best when used within 72 hours as efficacy significantly declines after this timepoint 1, 2, 4

• Combined estrogen-progestin (Yuzpe method): Least effective with higher side effect burden; only useful when dedicated methods unavailable 1, 4

Clinical Decision Algorithm

Within 72 hours of unprotected intercourse:

• Cu-IUD remains first choice if patient appropriate and provider available 2
• UPA and levonorgestrel have similar effectiveness in this window, though UPA preferred for women with BMI ≥25 kg/m² 1, 2, 5
• Levonorgestrel advantage: available over-the-counter without prescription 6

Between 72-120 hours (3-5 days):

• Cu-IUD is first choice 2
• UPA is the ONLY effective oral option - levonorgestrel shows significantly reduced effectiveness at this timepoint 2, 4
• Do not use levonorgestrel or Yuzpe method at 5 days 2

Special populations:

• Overweight/obese women: UPA is more effective than levonorgestrel and should be preferentially used 1, 2, 5
• Women already on hormonal contraception: Emergency contraception remains effective and appropriate even when already using combined oral contraceptives or DMPA 2

Critical Timing Considerations After Use

After levonorgestrel:

• Resume or start regular hormonal contraception immediately 2
• Use barrier method or abstain for 7 consecutive days after restarting 2

After ulipristal acetate:

• Wait 5 days before starting or resuming hormonal contraception 2, 3
• Use barrier contraception or abstain for 14 consecutive days (or until next menses) 2, 5, 3
• Critical pitfall: Do not use additional levonorgestrel emergency contraception within 5 days of UPA, as progestin-containing contraceptives may impair UPA's ability to delay ovulation 3

After Cu-IUD:

• No hormonal interactions; provides immediate ongoing contraception 2

Common Pitfalls to Avoid

• Do not delay: All methods should be taken/inserted as soon as possible - effectiveness decreases with time 1, 3
• Do not repeat UPA in same cycle: Safety and efficacy of repeat use within the same menstrual cycle has not been evaluated 3
• Do not use UPA with CYP3A4 inducers (rifampin, St. John's wort, phenytoin, carbamazepine): These significantly decrease UPA plasma concentrations 3
• Vomiting within 3 hours: Consider repeating the dose 3
• Pregnancy test if menses delayed >1 week: Rule out pregnancy if expected period does not occur within 1 week of anticipated date 3

Important Counseling Points

• Emergency contraception does not protect against sexually transmitted infections including HIV 1, 3
• Emergency contraception is for occasional use only and should not replace regular contraception 3
• Menstrual cycle changes are common: menses may occur earlier or later by several days (7% report >7 days early, 19% report >7 days late with UPA) 3
• Consider ectopic pregnancy if lower abdominal pain develops 3-5 weeks after taking emergency contraception 3
• Advance provision of emergency contraception may increase likelihood of timely use 2