Smoking a cigarette or having intercourse after taking Unwanted 72 (levonorgestrel) will not reduce the medication's effectiveness for your previous intercourse. However, please know that emergency contraception only protects you from intercourse that happened *before* taking the pill. It does not prevent pregnancy from any sex that occurs *after* you take it. Because you had intercourse four hours later, you may not be protected for that specific act. I highly recommend using a barrier method, like condoms, for any further intimate contact. Please consider speaking with a healthcare provider for personalized guidance.