ella, or ulipristal, is an emergency contraceptive used for prevention of pregnancy following unprotected intercourse or a known or suspected contraceptive failure. This medication affects how progesterone works in the body and is thought to delay or prevent ovulation. It can be taken up to 5 days after unprotected sex with no decrease in effectiveness. When taken as directed, ella is more effective in preventing pregnancy than other emergency contraception pills (progestin-only or combined EC pills). ella is available by prescription only. It is not intended for routine use as a contraceptive and will not terminate an existing pregnancy.
For more information you can also check out the ella website.