sychiatrists, pediatricians and family practice doctors said in interviews that they would restrict their use of antidepressants in the wake of a federal advisory committee's decision that the medicines should contain severe warnings about the risks of suicide.

Dr. Alexander Lerman, a child and adolescent psychiatrist in New York City, said that he would no longer prescribe the medicines to some children and that for the rest he would sit down with their parents and discuss in detail the risks of the drugs.

The advisory committee made its recommendation after reviewing numerous studies of antidepressants. Although no children in any study of the drugs committed suicide, there were reports of increased suicidal thoughts and behavior. The risks are greatest in the first weeks of therapy.

"Some parents are very uncomfortable with their kids being on medication to begin with," Dr. Lerman said, "and this will be enough so that some parents will not allow their kids to be on medicines."

Meanwhile, top officials at the Food and Drug Administration have decided to re-evaluate whether the drugs can cause adults to become suicidal, too. Dr. Janet Woodcock, the agency's deputy commissioner of operations, said in an interview that for years the F.D.A. had largely evaluated the risk of suicide in adults by analyzing the final outcomes of antidepressant trials. That analysis has shown no link to suicide or suicidal behavior, she said.

But the agency identified the risk of suicidal thoughts and behavior in the trials involving teenagers and children by analyzing in a new way the adverse-event information provided with the trials. The agency is now gearing up to do the same thing in its adult trials, a database that includes 234 tests with more than 40,000 patients.

"I think there might be more to be learned, based on what we learned from the pediatric studies," Ms. Woodcock said.

In the meantime, doctors will have to struggle with how to treat depressed children and teenagers. There are few good options. While data from 24 studies of nine drugs provided wildly different estimates of each drug's benefits and risks, the advisory committee decided that the studies were so small that there was no convincing evidence that any drug was safer than another. And studies that included one-on-one talk-therapy failed to show any benefit for that treatment.

The advisory committee decided that the suicide warning should also be placed on the physician prescribing sheets for an older set of antidepressants called tricyclics. These medicines have largely fallen out of favor because of the damage they can do to patients' hearts and the risks that result from overdoses.

The warning was extended to them in part because of the "great risk in scaring clinicians back to the tricyclics," said Dr. Thomas Laughren, a top agency official.

Indeed, committee members openly worried throughout their deliberations that their decision might lead some physicians to stop treating depression in children and teenagers. In interviews, some clinicians said the committee's push for a warning had done just that.

"I can tell you that my writing for antidepressants for kids has dropped off dramatically," said Dr. Phillip Kennedy, a family practice physician in Augusta, Ga.

"It used to be that when I saw a kid who was 14, 15 or 16 and who was really down, I felt very comfortable writing them an S.S.R.I. prescription," Dr. Kennedy said, referring to a class of antidepressants. "I don't now."

Whether antidepressant prescriptions for children and teenagers will really decline is unclear. In March, the F.D.A. issued a vaguely worded warning about suicide risk, and it had no impact on prescriptions trends, agency officials said. Nearly 11 million prescriptions for antidepressants were given to children and teenagers in 2002, and that total has since been growing steadily. In the first six months of this year, the number of such prescriptions grew almost 8 percent.

Indeed, worldwide sales of antidepressants in the 12-month period ending in March were $19.97 billion, according to IMS Health, a pharmaceutical information and consulting company, making them among the biggest selling drugs.

Most physicians have written scores of prescriptions for the pills with no ill effects. And since doctors are unable to distinguish between a drug and a placebo effect, many feel the drugs work quite well. In fact, the drugs have by and large not proven any more effective in children and teens than placebos, and even in adults prove better than placebos in only half of all studies.

Still, the warning that the advisory committee is recommending, a so-called black-box warning on the label that explicitly talks of the suicide risk, is a serious precautionary measure, and physicians said in interviews that the promise of such a warning has gotten their attention. The risk of suicide from the drugs is small. If 100 children and teenagers are given the drugs, two or three will become suicidal who would not have been suicidal if given placebos.

Dr. Albert Melaragno, a pediatrician in Valencia Calif., said that five years ago he never prescribed antidepressants. But, Dr. Melaragno said, the scarcity of psychiatrists and the growing unwillingness of managed-care plans to pay for mental-health services has thrust the task of dealing with depressed children and teenagers onto him.

The new warning will lead him to be more cautious in using the pills and more likely to refer patients to psychiatrists, he said. But he feared that many patients who need the medicines will now refuse therapy.

"It's raised such a specter with patients that more of the teens who have the need for treatment will be frightened off of using it and suffer more because of that," Dr. Melaragno said.

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