I'm not an expert but I found the following information for you.
"There are no major side effects associated with i-Pill use. The most common side effects are nausea, vomiting, breast tenderness, fatigue, headache, abdominal pain, and menstrual changes. One way to avoid nausea and vomiting is to take an over-the-counter anti-nausea medication about 1 hour before taking the i-Pill.
Most women can expect a normal period within one month after taking the pill, but it's possible for the next period to come one week earlier or later than expected. Intermenstrual bleeding is rare. "
You may want to avoid unprotected sex not only for birth control reasons but also for avoiding STDs.
Sex is much more fun when it's disease free! :-)