What are the options for emergency contraception after unprotected sex?

Emergency Contraception Options After Unprotected Sex

Four emergency contraception options are available in the United States: the copper IUD (most effective), ulipristal acetate 30 mg (most effective oral option through 5 days), levonorgestrel 1.5 mg (effective within 72 hours), and combined estrogen-progestin regimen (least effective, rarely used). 1

Recommended Approach Based on Timing and Patient Factors

Within 72 Hours (0-3 Days) After Unprotected Sex

For normal weight women (BMI ≤30 kg/m²):

• Copper IUD remains the most effective option at any timepoint with <1% failure rate 2, 3
• Levonorgestrel 1.5 mg single dose is appropriate and effective, with pregnancy rates of 1.9% when taken within 72 hours 4
• Ulipristal acetate 30 mg is also highly effective within this window 1, 4

For women weighing >165 pounds or BMI >30 kg/m²:

• Ulipristal acetate 30 mg is significantly more effective than levonorgestrel in this population 2, 3
• For levonorgestrel in obese women (BMI >30), observed pregnancy rate was 7.4% compared to expected 4.4%, suggesting reduced effectiveness 4
• For ulipristal acetate in obese women (BMI >30), observed pregnancy rate was 3.1% compared to expected 4.5% 4
• The copper IUD remains the most effective option regardless of weight 2, 3

Between 72-120 Hours (3-5 Days) After Unprotected Sex

The clinical algorithm changes significantly after 72 hours:

• Ulipristal acetate 30 mg is the only effective oral option at this timepoint, maintaining consistent efficacy throughout the full 120-hour window 1, 2
• Levonorgestrel has significantly reduced effectiveness after 72 hours, with pregnancy rates increasing at 4-5 days 1, 3
• The copper IUD can be inserted within 5 days of unprotected intercourse and remains the most effective option 1, 2
• When the day of ovulation can be estimated, the copper IUD can be inserted beyond 5 days after intercourse, as long as insertion occurs ≤5 days after ovulation 1

Specific Dosing Regimens

Ulipristal Acetate (Ella)

• Single 30 mg dose taken as soon as possible within 120 hours (5 days) 1, 4
• Reduced pregnancy rate from expected 5.5% to observed 2.2% when taken 48-120 hours after intercourse 4
• No significant differences in pregnancy rates across five 24-hour intervals from 0-120 hours 4

Levonorgestrel

• Single 1.5 mg dose (preferred) OR two 0.75 mg doses taken 12 hours apart 1
• Should be taken as soon as possible within 72 hours 1
• The single 1.5 mg dose has equivalent efficacy to the split-dose regimen and improves compliance 5

Combined Estrogen-Progestin Regimen

• Two doses: 100 μg ethinyl estradiol plus 0.50 mg levonorgestrel, repeated 12 hours later 1
• This regimen is less effective than ulipristal acetate or levonorgestrel and causes more side effects (nausea, vomiting), making it rarely recommended 1

Copper IUD

• Must be inserted by a healthcare provider within 5 days of unprotected intercourse 1
• Provides ongoing highly effective contraception after insertion 1, 2

Critical Post-Administration Instructions

After Ulipristal Acetate Use:

• Any regular contraceptive method can be started immediately, BUT barrier contraception or abstinence is required for 14 consecutive days (or until next menses) 1, 2, 3
• Do not use additional levonorgestrel emergency contraceptive pills within 5 days of ulipristal acetate intake 4
• Advise pregnancy test if withdrawal bleed does not occur within 3 weeks 1

After Levonorgestrel Use:

• Resume or start regular contraception immediately, BUT use barrier method or abstain for 7 consecutive days 1, 2, 3
• Advise pregnancy test if withdrawal bleed does not occur within 3 weeks 1

After Copper IUD Insertion:

• No hormonal interactions with existing contraceptive use 2
• Provides immediate ongoing contraception 1

Important Clinical Caveats

Vomiting within 3 hours:

• If vomiting occurs within 3 hours of taking any oral emergency contraceptive pill, another dose should be taken 4
• Contact healthcare provider immediately to discuss repeat dosing 4

Existing hormonal contraception:

• Emergency contraception can and should be used even when already on combined oral contraceptives or depot medroxyprogesterone acetate if unprotected intercourse or contraceptive failure has occurred 2
• Existing hormonal contraception does not interfere with emergency contraception effectiveness 2

Advance provision:

• An advance supply of emergency contraception may be provided to ensure availability and timely use 1, 2
• Advance provision increases use 2-7 times but does not reduce pregnancy rates in clinical trials, as timing remains critical 1

Ectopic pregnancy risk:

• Advise patients to seek medical attention for severe lower abdominal pain 3-5 weeks after taking emergency contraception to evaluate for ectopic pregnancy 4

STI protection:

• Emergency contraception does not protect against HIV or other sexually transmitted infections 4