"Before you become alarmed that medication isn't working," says Dr. Larry Silver, "make sure your child is really taking it." Peer pressure to conform increases in early adolescence, and many kids who took medication without any problem when they were younger suddenly feel singled out when they have to leave the classroom to visit the school nurse. They may "forget" to go, or may refuse to take the medication.
If you know that your child is taking medication as prescribed and the medication still appears to be not working, then visit your doctor. Depression and other health problems can make it appear as if medication isn't working.