Emergency Contraception After Combined Levonorgestrel/Ethinyl Estradiol
No, you should not give an additional levonorgestrel 1.5mg pill after a combination of levonorgestrel and ethinyl estradiol (Yuzpe regimen) has already been administered for the same episode of unprotected intercourse. The standard emergency contraception dose has already been delivered, and adding more levonorgestrel does not improve efficacy and only increases side effects 1, 2.
Why Additional Levonorgestrel Is Not Indicated
The mechanism of action of levonorgestrel (delaying ovulation) has biological limits that cannot be overcome by increasing the dose beyond the standard 1.5mg. 1 The Yuzpe regimen already contains 1.0mg of levonorgestrel total (0.5mg per dose × 2 doses), which approaches the standard levonorgestrel-only dose of 1.5mg 3, 4.
Key Pharmacologic Considerations
Both regimens work through the same mechanism: delaying or blocking the LH surge and interfering with ovulation 5. Adding more levonorgestrel after the Yuzpe regimen provides no additional ovulation suppression.
The Yuzpe regimen (100μg ethinyl estradiol + 0.5mg levonorgestrel × 2 doses) is already a complete emergency contraception course, though less effective and more poorly tolerated than levonorgestrel-only 4, 3.
Levonorgestrel efficacy is time-dependent, not dose-dependent. Pregnancy prevention rates are highest when taken within 72 hours, decreasing at 4-5 days regardless of dose 1, 3.
What To Do Instead
If Concerned About Efficacy
If the Yuzpe regimen was given but you're concerned about inadequate contraception, consider these alternatives rather than adding levonorgestrel:
Within 120 hours (5 days) of intercourse: Offer ulipristal acetate (UPA) 30mg, which is significantly more effective than levonorgestrel 3-5 days post-intercourse (65% lower pregnancy risk in first 24 hours) 1. However, note that UPA should ideally not be given immediately after levonorgestrel due to potential antagonism 3.
Within 5 days of intercourse: Copper IUD insertion is the most effective emergency contraception method with <1% failure rate, regardless of timing or patient weight 1, 3.
If Vomiting Occurred
The only scenario where repeating emergency contraception is appropriate is if vomiting occurred within 3 hours of taking either dose of the Yuzpe regimen:
- Repeat the vomited dose as soon as possible 3
- Consider using an antiemetic (meclizine or metoclopramide) before the repeat dose 3, 4
- Alternatively, switch to levonorgestrel-only 1.5mg, which causes significantly less nausea and vomiting than the combined regimen 3
Clinical Algorithm for This Scenario
When a patient has already received the Yuzpe regimen:
Confirm timing: Was the Yuzpe regimen completed within 5 days of unprotected intercourse? 3
Assess for vomiting: Did vomiting occur within 3 hours of either dose? 3
- Yes: Repeat the vomited dose with antiemetic
- No: Proceed to step 3
Evaluate efficacy concerns:
- Patient weight >165 lbs AND still within 120 hours: Consider UPA 30mg as it's more effective in heavier women 1, 3
- Beyond 72 hours but within 120 hours: Consider UPA 30mg, which maintains effectiveness throughout the full 5-day window 1
- Any timepoint within 5 days: Offer copper IUD for maximum efficacy 1
Do NOT add levonorgestrel 1.5mg to an already-completed Yuzpe regimen 1, 2
Important Follow-Up
After any emergency contraception regimen:
- Advise pregnancy test if no withdrawal bleed within 3 weeks 3
- Resume or initiate regular contraception immediately, but use barrier method or abstain for 7 days after levonorgestrel/Yuzpe regimen 3
- Counsel that emergency contraception is a backup method, not for ongoing use 6
Common Pitfall to Avoid
Do not confuse "inadequate dosing" with "method failure." The Yuzpe regimen, while less effective than levonorgestrel-only (preventing ~75% vs ~85% of pregnancies), is still a complete emergency contraception course 4. Adding levonorgestrel afterward does not compensate for the inherent lower efficacy of the Yuzpe method and is not supported by any guideline 1, 2.