The first several periods are almost always painless. Once a girl begins to ovulate, she may experience some discomfort before, during or after her period. Common symptoms include cramping, bloating, sore or swollen breasts, headaches, mood changes and irritability, and depression.
Menstrual cramps, probably the most bothersome effect, can range from mild to moderate to severe. If you have pain in the lower abdomen or back, talk to your pediatrician, who may recommend exercises and an over-the-counter pain medication such as ibuprofen.