xiromed's levonorgestrel emergency contraceptive pill can reduce the chance of pregnancy after unprotected sex. it is highly recommended to take as soon as possible. results are greater if taken within 72 hours of unprotected sex, but the sooner the better. levonorgestrel will not harm an existing pregnancy. each table constrains 1.5mg of levonorgestrel. compare to active ingredients in plan b one-step.