What is the recommended use and dosage of Levonorgestrel (emergency contraceptive) for contraception?

Levonorgestrel Emergency Contraception: Recommended Use and Dosage

Levonorgestrel should be administered as a single 1.5 mg dose or as two 0.75 mg doses (either 12 or 24 hours apart) taken as soon as possible within 5 days of unprotected intercourse, though efficacy significantly declines after 72 hours. 1

Dosing Options

Levonorgestrel can be administered using either of these equivalent regimens:

• Single dose: 1.5 mg taken once 1, 2
• Split dose: 0.75 mg followed by a second 0.75 mg dose, which can be taken either 12 or 24 hours after the first dose 1, 3

The single 1.5 mg dose is preferred for convenience, as both regimens have equivalent efficacy and side effect profiles. 2

Timing and Efficacy

Levonorgestrel must be taken as soon as possible after unprotected intercourse for maximum effectiveness. 1

Time-dependent efficacy:

• Within 72 hours (3 days): Most effective period, with pregnancy rates remaining low 1, 4
• 72-96 hours (days 4-5): Efficacy significantly decreases, with pregnancy rates increasing at 4-5 days 1
• 96-120 hours (day 5): The odds of pregnancy increase more than five-fold compared to administration within 24 hours 4

While levonorgestrel can be used up to 5 days (120 hours) after unprotected intercourse, it should not be the preferred option at this timepoint due to substantially reduced effectiveness. 1, 5

Comparison with Other Emergency Contraception Options

When counseling patients, consider these alternatives based on timing:

• Cu-IUD: Most effective option at any timepoint up to 5 days, and provides ongoing contraception 1, 5
• Ulipristal acetate (UPA): More effective than levonorgestrel when taken 3-5 days after unprotected intercourse, maintaining consistent efficacy throughout the full 120-hour window 1, 5
• Levonorgestrel: Comparable to UPA within the first 3 days, but significantly less effective after 72 hours 1

Important Clinical Considerations

Starting Regular Contraception After Use

Any regular contraceptive method can be started immediately after levonorgestrel use. 1

• The patient must use barrier contraception or abstain from intercourse for 7 days after starting regular contraception 1
• Advise pregnancy testing if withdrawal bleeding does not occur within 3 weeks 1

Special Populations

Levonorgestrel may be less effective in obese women compared to UPA. 1

Advance Provision

Providing an advance supply of levonorgestrel is safe and increases the likelihood of timely use when needed. 1

• Advance provision does not negatively affect regular contraceptive use patterns, pregnancy rates, or STD incidence 1
• This allows patients to take the medication as soon as possible after unprotected intercourse 1

Common Pitfalls to Avoid

• Do not delay administration: Every 24-hour delay reduces efficacy, with dramatic decline after 72 hours 4
• Do not recommend levonorgestrel as first-line at 5 days: UPA or Cu-IUD are superior options at this timepoint 1, 5
• Do not confuse with the Yuzpe regimen: Combined estrogen-progestin regimens are less effective and cause more side effects than levonorgestrel 1
• Do not withhold due to concerns about future contraception: Levonorgestrel does not interfere with immediately starting regular hormonal contraception, unlike UPA which requires 14 days of barrier use 1