Taken from OptionLine
“Emergency contraception is a type of birth control you can take after you have unprotected sex. Sometimes it’s referred to as the morning-after pill. There are two types commonly available: Plan B One-Step® (and others like it) and ella®.
Both kinds of emergency contraception can be used up to five days after unprotected sex, but Plan B One-Step becomes less effective over time. You can buy some types of emergency contraception without a prescription, but other types do require a prescription.
If you think you might be pregnant, you may want to take a pregnancy test before taking emergency contraception. Both types of morning-after pills can cause an abortion, depending on when you take them and when you had unprotected sex.
Plan B One-Step, ella, and other forms of emergency contraception are not recommended if you are pregnant, and can actually hurt you if you take them while you are pregnant.”