FRIDAY, Nov. 23 (HealthDay News) -- When kids have academic problems, report cards make that clear to parents. And if a kid skins a knee or breaks a bone, parents know what to do.

But detecting that a child is being bullied, and then knowing how to react, may not be so clear-cut.

Kids often are reluctant to tell their parents they're being bullied, making it difficult to know that they're having trouble with other kids at school or online.

One thing that's very clear, however, is that bullying is not a rare occurrence. About one in five kids reports being bullied at school in the past 12 months, and another 16 percent have been harassed online, according to a survey from the U.S. Centers for Disease Control and Prevention. The CDC also found that 6 percent of children and teens didn't go to school at least once in the previous month because they were concerned for their safety.

Bullying "eats away at a young person's self-esteem," said Dan Rauzi, a national bullying expert and senior director of technology programs at the Boys & Girls Clubs of America. "It can cause them to not want to go to school or get on the bus, they may not want to go online and it affects learning in school."

Bullying also interferes with a child's social, emotional and academic development, according to the American Academy of Child and Adolescent Psychiatry. Sometimes the harassment is so severe that bullying victims commit suicide, the academy reports.

So, what signs should a parent be watching for?

A child who's being bullied may be more anxious and fearful, perhaps wanting to avoid school and social settings, according to Victor Gardner, a child and adolescent psychologist with the Henry Ford Health System in Detroit.

Children may complain of headaches, stomachaches and nausea, he said. Or, they may develop low self-esteem and lack confidence. Grades may drop, too. If the bullying is occurring online, the child might stop participating in favorite online activities.

Some signs are more obvious, such as unexplained bruising, torn clothing, missing items -- such as books, electronics or jewelry -- and noticeable changes in eating habits. For instance, bullying experts say that kids might eat a great deal when coming home from school because they didn't eat lunch because of some type of bullying.

"If you notice behavioral changes -- a previously happy child now seems sullen, angry and upset -- ask what's going on," Rauzi said. "Don't take the standard 'Nothing' or 'I'm fine' response. One of the reasons that young people don't tell adults what's going on is that they don't think anything will happen."

Ideally, parents will have had discussions about bullying with their children before it occurs, Gardner said. "When children are going off to a new school or a sleep-away camp, or they're showing an increased interest in going online, be open and honest with them about the things that could happen," he said. "Tell them when it's appropriate to speak up and who to tell. If you have that talk, and review it when school starts, it helps to encourage the lines of communication."

Knowing what steps to take to stop a bully can be somewhat trickier. For starters, kids often don't want their parents to get involved at all.

In this case, Gardner said, let the child know that you're glad he or she told you what was going on and that you'd like to talk about what your child has done to try to reduce the bullying behavior. Help the child assess whether those steps are working, and let your child know that anytime it becomes overwhelming, you're willing to step in.

He suggests asking your child what he or she thinks the next steps should be if the bullying doesn't subside. Does your child want to talk to a counselor? Would he or she like to have both sets of parents and children meet with school officials?

Rauzi said it's also important to distinguish between bullying and youth conflict.

"You can engage in conflict with your peers, and that's not necessarily bullying," Rauzi said. "Bullying is not just a one-shot deal. Getting picked on repeatedly is bullying. If there's an imbalance of power, one kid is physically bigger or more socially connected or more tech savvy, that's bullying. But, it's important that parents know the difference and they shouldn't jump into every youth conflict situation," he noted.

"We can help them work through a conflict," he said, "but bullying needs adult intervention."

Rauzi said it's also good to keep in mind that children and teens are pretty resilient. If the bullying stops and kids can re-establish their social networks, they probably won't have lasting damage from bullying.

Of course, that's not always the case. As Gardner said, "adults need to remember that bullying isn't just a case of 'kids will be kids.'"

Gardner pointed out that "there can be significant and life-threatening consequences when bullying occurs, and children need the support of their parents and school, and they need to intervene as soon as possible."

More information

Pacer's National Bullying Prevention Center has more about bullying.

A companion article details one teen's stand against bullies.

SOURCES: Dan Rauzi, senior director, technology programs, Boys & Girls Clubs of America; Victor Gardner, Psy.D., child and adolescent psychologist, Henry Ford Health System, Detroit

Copyright © 2012 HealthDay. All rights reserved.