The effectiveness of the morning after pill varies depending on the type of pill and how quickly it is taken after unprotected sex. Generally:
- Levonorgestrel pills (e.g., Plan B) are up to about 89-95% effective if taken within 24 hours , around 85% effective if taken within 1 to 2 days, and about 58% effective if taken within 72 hours (3 days). Its effectiveness decreases the longer the delay after unprotected sex, and it is not effective beyond 72 hours.
- Ulipristal acetate pills (e.g., ellaOne) can be effective up to 120 hours (5 days) after unprotected sex and may maintain effectiveness better over that period.
- Overall, emergency contraception reduces the risk of pregnancy by approximately 59% to 98% depending on timing and type.
- The pill works mainly by preventing or delaying ovulation, but it is ineffective if ovulation has already occurred.
- It should be taken as soon as possible for maximum efficacy.
- The morning after pill does not provide ongoing contraception; further protection methods should be used if having sex subsequently.
In summary, the morning after pill is highly effective if taken promptly, especially within 24 hours, but less so as time passes, and effectiveness varies by pill type.
