Here are some signs to look for in your children to help you determine if they are drunk or high.

Warning signs of teenage alcohol and drug abuse may include:*

Physical	Fatigue, repeated health complaints, red and glazed eyes, and a lasting cough.
Emotional	personality change, sudden mood changes, irritability, irresponsible behavior, low self-esteem, poor judgment, depression, and a general lack of interest.
Family	starting arguments, breaking rules, or withdrawing from the family.
School	decreased interest, negative attitude, drop in grades, many absences, truancy, and discipline problems.
Social problems	new friends who are less interested in standard home and school activities, problems with the law, and changes to less conventional styles in dress and music.

* For additional info:

American Acadamy of Child and Adolescent Psychiatry

Aspen Education Group (includes signs of specific drug use)