When Alesse (Levonorgestrel) Becomes Effective for Pregnancy Prevention
Alesse requires 7 consecutive days of consistent use before it becomes effective at preventing pregnancy if started more than 5 days after the start of menses. 1
Timing Based on When You Start
Starting Within 5 Days of Menses
- No backup contraception needed if Alesse is initiated within the first 5 days after menstrual bleeding begins 1
- The pill is immediately effective in this scenario 1
Starting More Than 5 Days After Menses
- Backup contraception is required for 7 consecutive days if starting beyond day 5 of the menstrual cycle 1
- Use barrier methods (condoms) or abstain from intercourse during this 7-day period 1
- After 7 days of consistent pill use, full contraceptive protection is established 1
Critical Implementation Points
The 7-day rule applies to continuous, correct use - missing pills during this initial period resets the timeline and requires restarting the 7-day backup period 1
Common Pitfall to Avoid
- Do not assume immediate protection when starting Alesse at any random point in your cycle 1
- The most common error is having unprotected intercourse during the first week when starting mid-cycle, which carries significant pregnancy risk 1
If Unprotected Intercourse Occurs During the First 7 Days
- Emergency contraception should be considered, especially if intercourse occurred in the previous 5 days 1
- Levonorgestrel emergency contraception (Plan B) can be taken up to 120 hours after unprotected intercourse, though effectiveness decreases over time 1, 2, 3
Switching From Another Method
When switching to Alesse from another contraceptive method, 7 days of backup contraception is needed only if more than 5 days have passed since starting menses 1