I had unprotected sex on the 21st day of my menstrual cycle, immediately after i took levonorgestrel pills. i'm i safe? this happened yesterday by 4pm

Quite effective: Emergency contraception (EC) pills are used after sex to lower the chance of pregnancy by about 70-80%. EC is a high dose of birth control hormones. Irregular bleeding or spotting is a common side effect. Nausea, abdominal pain or cramping, and fatigue may occur, but symptoms resolve in a day or two as the drug leaves the body soon. A home urine pregnancy test should be done 3 weeks after sex.