what does plan b do to your body

Plan B One-Step is a type of morning-after pill that can be used after unprotected sex to prevent pregnancy. It contains the hormone levonorgestrel, which can prevent ovulation, block fertilization, or keep a fertilized egg from implanting in the uterus. Plan B is intended for backup contraception only, not as a primary method of birth control. Some possible side effects of Plan B include a heavier next period, nausea, stomach pain, headache, breast tenderness, and a delayed period. Plan B only works to prevent pregnancy and cannot end one. It is important to note that Plan B is not effective in preventing sexually transmitted infections (STIs) .