Increasingly, schools are embarking on drug testing, particularly of student-athletes, following a 2002 US Supreme Court ruling that declared the practice legal.
Parents may also be tempted by newly available home drug screening kits in an effort to catch the problem early.
But the American Academy of Pediatrics, updating its decade-old policy statement on the issue, said screening for illicit drugs is a complicated process prone to errors and cheating, and has not been shown to curtail youngsters' drug use.
Drug testing also creates a counterproductive climate of ''resentment, distrust and suspicion'' between children and their parents or school administrators, a committee of experts wrote in the March issue of the group's journal, Pediatrics.
False-positive results can arise from eating poppy seeds or ingesting certain cold medications, and test results may need to be confirmed with expensive further testing, it said.
Many students are also likely to be aware of Web sites that offer methods of defeating drug testing.
In addition, several illegal drugs are undetectable in urine more than 72 hours after use, and standard tests do not detect often abused substances such as alcohol, Ecstasy and inhalants. Some youngsters may respond to testing by avoiding drugs such as marijuana and instead abuse less-detectable, but more dangerous, drugs, the statement said.
''A key issue at the heart of the drug-testing dilemma is the lack of developmentally appropriate adolescent substance abuse and mental health treatment'' in many communities, it said, noting existing programs designed for adults may be unsuitable for children.
The report suggested parents suspicious that a child is abusing drugs or alcohol consult the child's primary care doctor rather than rely on school-based drug screening or home kits to check their concerns.
REUTERS AKJ RN1043