Recommended Dose of Plan B (Levonorgestrel) for Emergency Contraception
The recommended dose of Plan B (levonorgestrel) for emergency contraception is a single 1.5 mg dose taken as soon as possible within 5 days after unprotected sexual intercourse. 1, 2
Administration Details
- Plan B is available as a single 1.5 mg pill (Plan B One-Step) or as two 0.75 mg pills (Next Choice) 1, 3
- If using the two-dose regimen (0.75 mg pills), both doses can be taken at the same time without decreasing efficacy or increasing side effects 1, 2
- The medication should be taken as soon as possible after unprotected intercourse to maximize effectiveness 2
- While Plan B is most effective when taken within 72 hours (3 days), it can still be effective when taken up to 120 hours (5 days) after unprotected intercourse 1, 2
Effectiveness Considerations
- Treatment initiated within 72 hours reduces pregnancy risk by at least 75% 2
- Effectiveness decreases as time passes after unprotected intercourse 2
- Pregnancy rates are low when Plan B is administered within 4 days but increase at 4-5 days after unprotected intercourse 1, 2
- Plan B may be less effective in women with higher body weight (>165 pounds), though it should still be offered 1, 2
Important Clinical Considerations
- If vomiting occurs within 3 hours of taking Plan B, another dose should be taken as soon as possible 2
- Any regular contraceptive method can be started immediately after using Plan B 1, 2
- Ulipristal acetate (30 mg) may be more effective than levonorgestrel, particularly after 72 hours and for women who are overweight or obese 1, 3
- The copper IUD is the most effective emergency contraception option (failure rate <1%) and can be inserted within 5 days of unprotected intercourse 1
Advance Provision
- An advance supply of Plan B may be provided so it will be available when needed and can be taken as soon as possible after unprotected intercourse 1, 2
- Studies show that advance provision increases use of emergency contraception but does not adversely affect regular contraceptive behavior 2
Plan B is a safe and effective emergency contraceptive option that should be taken as a single 1.5 mg dose as soon as possible after unprotected intercourse, though it remains effective for up to 5 days afterward.