Types of Emergency Contraception Available
Four types of emergency contraception are available in the United States: the copper IUD (Cu-IUD), ulipristal acetate pills, levonorgestrel pills, and combined estrogen-progestin pills. 1
Emergency Contraceptive Pills (ECPs)
The three oral emergency contraceptive options differ in their formulations and effectiveness:
1. Ulipristal Acetate (UPA)
- Single 30 mg dose
- Most effective oral emergency contraceptive, particularly 3-5 days after intercourse
- Can be used up to 120 hours (5 days) after unprotected sex
- Maintains effectiveness better than levonorgestrel in obese women 1
- Available by prescription only 2
2. Levonorgestrel (LNG)
- Available as either a single 1.5 mg dose or split dose (two 0.75 mg tablets taken 12 hours apart) 1, 3
- The split-dose regimen can be taken as a single dose with no decrease in efficacy 4
- Must be taken within 72 hours of unprotected intercourse for FDA approval, though some effectiveness extends to 120 hours 3
- Available over-the-counter for women 17 years and older; prescription required for younger women 3
- Important caveat: Effectiveness may be reduced in obese women compared to UPA 1
3. Combined Estrogen-Progestin (Yuzpe Method)
- Two-dose regimen: 100 μg ethinyl estradiol plus 0.50 mg levonorgestrel per dose, taken 12 hours apart
- Least effective oral option and associated with more side effects (nausea and vomiting) compared to UPA or levonorgestrel 1
- Useful only when dedicated emergency contraceptive products are unavailable 5
Copper Intrauterine Device (Cu-IUD)
Most Effective Emergency Contraception Method
- Can be inserted within 5 days of unprotected intercourse
- When ovulation timing is known, can be inserted beyond 5 days after sex, as long as insertion occurs within 5 days of ovulation 1
- Highly effective as emergency contraception and provides the added benefit of ongoing long-term contraception 1, 6
- Requires bimanual examination and cervical inspection before insertion 7
Critical Timing Considerations
All emergency contraceptive pills should be taken as soon as possible within 5 days of unprotected intercourse 1. However, the evidence shows important differences in effectiveness over time:
- Within 3 days: UPA and levonorgestrel have similar effectiveness
- Days 3-5: UPA demonstrates superior effectiveness compared to levonorgestrel 1
- Pregnancy rates increase when levonorgestrel is taken after 3 days, with effectiveness declining at 4-5 days 1
Common Pitfalls to Avoid
Don't assume all oral methods are equally effective: The Cu-IUD is significantly more effective than any pill, followed by UPA, then levonorgestrel, with the Yuzpe method being least effective 6, 8
Consider body weight: In obese women, levonorgestrel may be less effective than UPA 1
Emergency contraception is not abortion: These methods work before implantation and will not terminate an existing pregnancy 3
No STI protection: Emergency contraception does not protect against sexually transmitted infections 3
Follow-up needed: If menses is delayed beyond 1 week after taking emergency contraception, pregnancy should be evaluated 3