How do you know your child's fear or anxiety is a reason to see a doctor? It usually involves extreme behavior. Experts offer these tips:

— Separation anxiety: This is not the clinginess often seen in toddlers. It's a level of fear in school-age children up to age 10 or 11 in which they may routinely follow a parent through the house and resist sleeping alone and going to school.

— Generalized anxiety: Affected kids, usually from grade school to early teens, often have many unrealistic fears that interfere with their lives. It may be worries about thunderstorms so severe that going outside even on sunny days provokes anxiety. They may be so anxious about being on time or doing well in school that it results in stomachaches or other physical complaints.

— Social anxiety or phobia: This may appear in grade school or adolescence and is often dismissed as shyness. But affected kids are so paralyzed by self-consciousness and fear of interacting with others that they avoid social situations or speaking in class. There may be physical symptoms, such as sweating or dizziness.

Many families learn to adjust their lifestyles to accommodate children with anxiety disorders. However, if untreated, the problems can morph into depression or substance abuse during the teen years, said Dr. John Walkup of Johns Hopkins Hospital. He's lead author of a study showing kids can improve substantially with the antidepressant sertraline, also sold as Zoloft, plus psychotherapy, or either treatment alone.

Click here to learn more about how counseling and Zoloft may help your child.