My birth control method failed. i've read that plan b works up to 72 hours after what if i wait 24 hrs after because my pharmacy is closed? am i safe?

Plan B: Yes - waiting 24 hours after sex is ok. 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.