Is a higher dose of levonorgestrel (a form of emergency contraception) more effective than the standard 1.5mg dose?

Is Higher Dose Levonorgestrel Better for Emergency Contraception?

No, higher doses of levonorgestrel above the standard 1.5 mg are not recommended or shown to be more effective for emergency contraception. The established dose is 1.5 mg taken as a single dose (or split as 0.75 mg twice, 12 hours apart), and this remains the standard 1.

Standard Levonorgestrel Dosing

• The recommended dose is 1.5 mg as a single dose, which can be given as one 1.5 mg pill or two 0.75 mg pills 1.
• When given as a split dose (0.75 mg twice), the second dose can be taken 12-24 hours after the first without compromising efficacy 2.
• Single-dose administration (1.5 mg at once) has similar effectiveness to the split-dose regimen and offers better convenience 2, 3.

Why Not Higher Doses?

The evidence does not support using doses higher than 1.5 mg. The key limitation of levonorgestrel is not the dose itself, but rather timing and patient weight:

• Levonorgestrel effectiveness decreases significantly after 72 hours, with pregnancy rates increasing at 4-5 days post-intercourse 1, 4.
• Levonorgestrel may be less effective in obese women regardless of dose 1.
• The mechanism of action (delaying ovulation) has biological limits that cannot be overcome simply by increasing the dose 5, 3.

When Levonorgestrel Is Insufficient

For situations where levonorgestrel is suboptimal, switch to a different method rather than increasing the levonorgestrel dose:

• Beyond 72 hours (3-5 days post-intercourse): Ulipristal acetate (UPA) 30 mg is significantly more effective than levonorgestrel, with 65% lower pregnancy risk in the first 24 hours and maintaining effectiveness throughout the full 120-hour window 1, 4, 6.
• For women weighing >165 pounds: UPA is more effective than levonorgestrel 1, 4.
• For maximum efficacy at any timepoint within 5 days: The copper IUD is the most effective emergency contraception method with <1% failure rate 1, 4.

Clinical Algorithm

Use this approach rather than considering higher levonorgestrel doses:

1. Within 72 hours + normal weight: Levonorgestrel 1.5 mg single dose is appropriate 1.
2. Within 72 hours + weight >165 lbs: Consider UPA 30 mg instead 1, 4.
3. Between 72-120 hours: UPA 30 mg is preferred; levonorgestrel has significantly reduced effectiveness 1, 4, 6.
4. Any timepoint if highest efficacy desired: Copper IUD insertion within 5 days 1, 4.

Important Caveats

• After levonorgestrel use: Resume regular contraception immediately but use barrier method or abstain for 7 days 1, 4.
• After UPA use: Can start regular contraception immediately but requires barrier method or abstinence for 14 days (or until next menses) 1, 4.
• Emergency contraception should be taken as soon as possible within the appropriate window, as efficacy decreases with time for all oral methods 1, 5.