how effective is plan b after 48 hours

Plan B (levonorgestrel emergency contraception) is less effective as time passes after unprotected sex. At 48 hours (2 days) after intercourse, typical effectiveness is around 61% to prevent pregnancy, with higher effectiveness if taken sooner and markedly reduced if taken after 72 hours. Taking it as soon as possible yields the best chance of preventing pregnancy; if you’re within 24 hours, effectiveness is much higher, and after 72 hours it’s generally considered not effective. If vomiting occurs within two hours of taking the dose, a repeat dose or an alternative method should be considered. For tailored advice, consider your specific cycle timing and whether ovulation has occurred, and consult a clinician if there are concerns or if you’re past the 72-hour window.