The side effects are mainly related to the second drug that's given, which causes contraction of smooth muscle. Contraction of the uterine muscle causes cramps and abdominal pain. Contraction of the muscles in the gastrointestinal tract can cause nausea, vomiting, and diarrhea. Another side effect is excessive blood loss from the uterus. The average duration of bleeding after the pills are given is about nine days, but some people can bleed for two to three weeks.
Some people can bleed fairly heavily, and have to have a surgical procedure to stop the bleeding.
The cost is very steep. It has to be given 24 hours after mid-cycle sexual intercourse. That's not what the drug was approved for by the Food and Drug Administration. It was approved to terminate an already established pregnancy that was in the uterus, after a woman knows she is pregnant and has a positive pregnancy test. This is totally different than the morning-after pill, which is emergency contraception, which occurs before the egg is fertilized.