The Medicines and Healthcare Products Regulatory Agency said on Wednesday a study of evidence from drug companies found that selective serotonin reuptake inhibitors, or SSRIs, concluded that the risks to those under 18 outweighed the benefits.
Of the type of drug, only fluoxetine, marketed as Prozac, was not included in the warning, the agency said.
These drugs are not licensed for use by under-18s, but an independent advisory group said it was known that some doctors independently decide to prescribe them to the young, based on their own judgment.
The Department of Health said on Wednesday 30,000 to 40,000 children and teenagers were prescribed SSRIs in the United Kingdom and about half of those were treated with Prozac.
The regulatory agency said side effects had been shown to include suicidal feelings, anxiety, insomnia, weight loss and headaches.
In October, the US Food and Drug Administration issued a health advisory alerting physicians to a possible link between antidepressant drugs and suicidal feelings in the young.
Only Prozac is approved in the United States for treatment of major depressive disorder in children.
Alasdair Breckenridge, chairman of the British agency, warned that patients on SSRIs should not suddenly stop taking them, but should talk to their doctor about treatment.
The drugs specified in the government announcement were sertraline (marketed in Britain as Lustral, and in the United States as Zoloft), citalopram (Cipramil or Celexa), escitalopram (Cipralex or Lexapro) and fluvoxamine (Favarin or Luvox).
Earlier this year, warnings were also given about the risks of paroxetine (Seroxat or Paxil) and venflaxine (Efexor or Effexor).
Warnings were also given about
risks of paroxetine, venflaxine
The regulatory agency said that left only fluoxetine, called Prozac, which appeared to have "a positive balance of risks and benefits" in treating under-18s.
Professor Gordon Duff, chairman of the independent advisory Committee on Safety of Medicines, said it had issued comprehensive advice on the use of these drugs in children after a thorough review of all the evidence available.
"This gives parents, young people and those who treat these devastating illnesses the information they need to make informed decisions about treatment," he said.
"None of these drugs has ever been licensed for use in those under 18," he said.
Data to be released
"We know, however, they are used in this age group outside of their licensed indications where prescribers make a judgment on their own responsibility that it is the correct treatment for a particular patient," he said.
The regulatory agency said it was going to release data from the clinical trials on SSRIs and children which had been supplied by the drug companies to allow doctors to assess the information on which the advice was based.
The expert group is continuing to focus on the safety of these drugs in adults.
Professor Ian Weller, chairman of the working group, said there was no evidence to suggest the risks of treatment outweighed the benefits in adults.