Schools are threatening to expel hyperactive children who do not take the controversial drug Ritalin, the BBC has learnt.
Ritalin is used to treat hyperactive children
Some parents are even being told that their children may be taken into care if they do not put their children on the drug.
The claims come as a survey in Scotland suggests some youngsters are selling Ritalin to drug dealers or swapping it for CDs and phone cards.
Parents' charity Overload Network International said the situation was so bad, some school secretaries and dinner ladies were having to hand out extra doses to children.
The survey also revealed that some teenage girls had started taking the drug as a diet pill.
Janice Hill of the charity has urged the government to step up controls of the drug to ensure it is not being abused.
Ritalin is prescribed to children with attention deficit hyperactivity disorder (ADHD).
The symptoms of ADHD range from poor concentration and extreme hyperactivity to interrupting and intruding on other people and not being able to wait in queues.
Studies have suggested the condition may affect one in 20 children. Boys are three times more likely to be diagnosed with ADHD than girls.
But Ritalin is also a mild stimulant - an amphetamine - that works on the central nervous system to improve concentration.
As a result, it is sometimes used by drug dealers to mix with amphetamine.
Nevertheless, studies have suggested the drug is an effective way of treating ADHD.
However, its critics say it can cause serious side-effects in some children, leaving them robotic, lethargic, depressed, or withdrawn.
As a result, many parents are refusing to allow their children to be given the drug.
However, the BBC has learnt that they are being pressured into changing their minds by schools.
The parents of teenager Ashley Aslett were told they would have to remove their son from his school in Lincoln if he didn't take Ritalin.
"They said Ashley was a danger to the school and other children and staff and if he wasn't to be medicated than he wouldn't be allowed in school," his father Simon told the BBC.
Ashley hadn't even been diagnosed with ADHD.
The school has since lifted its threat to exclude Ashley. However, Ashley decided against staying
Barry Turner, a law lecturer at the University of Lincoln, said the Asletts were not alone.
He told the BBC he had heard of similar cases and even of parents being told that their children would be put into care if they didn't take Ritalin.
"We haven't yet reached the stage it is at in some of the states of the United States, where parents have actually been prosecuted for child abuse because they haven't treated their children but we are becoming dangerously close to that state of affairs," he said.
The Department for Education said schools should not threaten to expel hyperactive children who did not take Ritalin.
"The prescription of Ritalin for a child is a decision to be discussed between parents and their family doctor or clinic," said a spokeswoman.
"It is not a matter on which schools should pass judgement."