Does plan b still works after a day i had sex?

Best within 24 hrs.: Plan B works best within 24 hours of unprotected intercourse.

Agree w Dr Ingram: Yes - this timing would be fine. Plan B One-Step is up to 89 % effective when taken within 72 hours (3 days) after unprotected sex. It can reduce chance of pregnancy by up to 95% if used within 24 hours. It continues to reduce the risk of pregnancy up to 120 hours (5 days) after unprotected sex, but is less effective as time passes.