Research from Britain is suggesting that an increasing number of children are being prescribed anti-psychotic drugs to treat a range of conditions which are not licensed for use in children.
The researchers say the long-term safety of using them for children for conditions such as hyperactivity and autism has not been established.
In a study by Professor Ian Wong from the London School of Pharmacy it was found that numbers grew from 0.39 per 1,000 under-18s in 1992 to 0.77 per 1,000 in 2005 and the largest increase was in the seven to 12 age group.
While some research has suggested that drugs such as ripseridone in some instances can be very effective in calming children with autism and helping with some behavioural problems, experts warn that such powerful drugs must be used with caution among the under 15s.
Professor Ian Wong says while these drugs can be very effective, the long-term consequences, especially on a young, developing brain, remain unknown.
Such drugs are licensed for use with adults but there is a dearth of clinical research to support their use in children except for certain conditions such as schizophrenia.
However doctors nevertheless can prescribe them for children using their own professional judgment and responsibility.
Some experts have suggested that as well as affecting a child's growing brain, there may also be implications for the cardiovascular system and such drugs also carry serious and harmful side-effects which need to be balanced against any benefit for the child or its parents; these include substantial weight gain and tardive dyskinesia (uncontrollable tongue and facial movements).
Professor Wong says parents should not take their child off the medication if it is working, but rather consult regularly with their doctor regarding the medication.
The research comes at a time when drugs such as Prozac and other anti-depressants have come under close scrutiny.
Wong says children on anti-psychotic medication are more likely to die earlier which though it may not be directly caused by the drug it is a concern.
The problem is greater in the U.S. where children as young as two are apparently being diagnosed with conditions such as Attention Deficit Hyperactivity Disorder (ADHD) and prescribed anti-psychotic drugs.
Professor Wong believes the UK is following the same trend as the number of children on the drugs has doubled since the early 1990s; but as yet he has not found any incidents of a child under four being placed on such drugs.
Experts say anti-psychotic drugs should only be used on children with extreme caution and very irregularly as they may cause heart, circulation and breathing problems and in general it was rarely necessary.
Anti-psychotics act on the brain chemical dopamine which is thought to play a role in cardiovascular regulation and some children in the States diagnosed with ADHD have suddenly died after being given stimulants which also act on the dopamine system.
The drug watchdog, the Medicines and Healthcare products Regulatory Authority (MHRA), says while it is concerned about the use of such drugs without evidence to prove they are safe in children it remains the responsibility of individual prescribers to decide whether the drugs would benefit a patient.