You can take Plan B (levonorgestrel emergency contraception) up to 5 days (120 hours) after unprotected sex, but it works best if taken within 3 days (72 hours). The effectiveness decreases the longer you wait to take it after sex
. Key points about timing and effectiveness:
- Plan B is most effective when taken as soon as possible after unprotected sex, ideally within 24 hours, with up to 89% effectiveness if taken within 3 days
- The FDA approves Plan B for use within 72 hours, but some studies suggest it may still reduce pregnancy risk up to 5 days after sex, though less effectively
- Plan B works primarily by delaying ovulation; if ovulation has already occurred, it will not prevent pregnancy
- Because sperm can live up to 5 days in the reproductive tract, taking Plan B early increases the chance of preventing fertilization
In summary, you should take Plan B as soon as possible after unprotected sex, but it can still be taken up to 5 days later with diminishing effectiveness
