In 41 states it is not a crime when a minor runs away from home. However, in nine states (Georgia, Idaho, Kentucky, Nebraska,
South Carolina, Texas, Utah, West Virginia, Wyoming) a child can be charged with running away. In these jurisdictions, a runaway is in violation of a "status offense". This means it is against the law only when someone under 18 years old does it. In your case, you reside in one of the nine states!
You can contact the police and have your child charged with this offense. You can also inform them of his purported drug abuse.
Once your child is located, he'll be brought before the juvenile court. He will be given help, if adjudicated as a delinquent.
Your son might also be classified as a habitual runaway in need of help. The court process has many different names, but it is commonly called a "Child in Need of Supervision" (CHINS) process. Runaway youth are considered CHINS in 34 states. The CHINS process can provide services to youth and families. CHINS can also result in punishment for the child. A child might receive a fine, suspended driving privileges, mandatory drug screening, probation, and incarceration in a juvenile facility. Children will also receive appropriate educational services and drug counselling.
http://74.125.47.132/search?q=cache....ppt+sc+runaway+laws&cd=5&hl=en&ct=clnk&gl=us
http://www.focusas.com/SouthCarolina.html