Morning After Pill (Emergency Contraception)

On that note, it's a terrible idea to use the morning-after pill too often, and if you find yourself needing it that often, get birth control. I know a lot of girls (myself included) that get really fucked up if they use it ONCE, let alone day after day, or week after week.

Expect some slight problems. I didn't get sick or nauseous, but my period had just ended a few days before and the day after I took it, I started bleeding again... for two weeks straight. That also screwed up my next period.
Although they do work (up to 72 hours after unprotected sex), they can cause problems and if her next period is late or screwed up, I wouldn't worry too much. It's definitely not something you'd want to use that often, and like I said, if you find yourself needing it that often, you need to get on some kind of birth control.
And like someone else said, they certainly are NOT an abortion pill. They prevent a fertilized egg from implanting in the lining of the uterus (like an IUD and some other contraceptives) but will not abort a pregnancy that has already occurred. If it were an abortion pill, you would need a prescription for them, and have to go back to the doctor every 24 hours for so many days to check up and make sure everything was going okay (like you do with the abortion pill).