Children as young as 12 have been treated for problems relating to alcohol and cannabis abuse, under a pilot programme run by the Irish Society for the Prevention of Cruelty to Children (ISPCC).
A very small number of teenagers, some as young as 14, have also been treated for problems with heroin use, while others aged 15-18 have been treated for ecstasy and cocaine problems.
Speaking after the publication of three-year statistics for the ISPCC Schoolmate programme, chief executive Paul Gilligan said the scheme illustrated that parents need to accept that every child or young person will come into contact with drugs and alcohol during their time at school.
More than 6,600 vulnerable children aged between seven and 18 have received treatment over the past three years under the support programme. It focuses on young people at risk of early school-leaving due to misuse of drugs and alcohol.
Cannabis and alcohol were the most frequently used drugs among 13- to 18-year-olds, with children with low self-esteem among those most likely to misuse drugs.
"I would go so far as to say that every child going into secondary school will be faced with a decision regarding drugs at some stage in their schooling," Mr Gilligan said. "That's different from, say, 10 years ago. Just as the internet and mobile phones are a fact of life, this is a fact of life.
"Parents need to not panic, but instead accept that dealing with drugs and alcohol is a core part of parenting."
A new leaflet for parents, also introduced yesterday by the ISPCC, advises that one of the best ways to prevent children misusing drugs and/or alcohol is to build their self-esteem from an early age.
Parents should try to delay the age their child takes their first drink; set firm but appropriate expectations; and be open in their discussion of the issue.
But it warns that a "just say no to drink and drugs" or "zero tolerance" approach does not work with young people. Instead, parents are advised to empower their children to make good and informed choices, and to encourage healthy pursuits.
If a parent suspects their child is taking drugs or alcohol, it is also important not to panic, and to be sure of their own beliefs around alcohol and drug use.
The Schoolmate service has been renamed the 4Me programme and is to be extended. Since 2003 it has provided 157 young people around the country with a minimum of two hours per week of individual counselling. A mentoring programme has also been put in place.