The Food and Drug Administration also stressed that patients of all ages should continue to be carefully monitored for signs of suicidal tendencies when they are beginning treatment on the drugs.
The label change proposed yesterday would expand a warning now on the antidepressants that applies only to children and adolescents.
The FDA presented its plan to update the drug labels at a meeting of outside advisers on the issue. They endorsed the plan.
Public reaction was split, with some saying the changes were overdue and others arguing they could keep drugs from those who need them.
In emotional testimony illustrated at times by slides of family photos, relatives of suicide victims pleaded for the new warnings.
Suzanne Gonzalez, shouting and in tears, goaded the panel to action, telling the experts that her 40-year-old husband who had been taking Paxil shot himself.
"I wake up every morning thinking, 'Oh my God, he's dead. He is freaking dead.' Do you wake up and think, 'How many people are going to die today because I am doing nothing?'" Gonzalez asked.
Still, mental health experts worry that additional warnings could curtail use of the drugs and ultimately do more harm than good.
Dr. John Mann, a Columbia University psychiatrist, suggested simply replacing the proposed expanded warnings with the recommendation that doctors more closely monitor their patients.
"We can do more good by providing more treatment for depressed children and adults," Mann said.
The FDA proposed the changes after completing a review that found use of the drugs may increase the risk of suicidal thoughts and behavior among young adults 18 to 24, as well as among younger patients.
Psychiatrists testified yesterday that the 2004 addition of a warning for children led to a falloff in antidepressant prescriptions being written for patients under 18 -- and an increase in suicides in that age group.
Still, overall use of antidepressants continues to grow, with nearly 190 million prescriptions dispensed in the United States last year, according to IMS Health, a health care information company. That suggests doctors have placed more weight on the long-term benefits of the drugs than on any short-term risks, said Dr. Thomas Laughren, director of the FDA's division of psychiatry products.
Expanding the "black box" or other warnings on the drugs could dissuade patients from seeking or starting treatment, mental health experts said. They warned that people with untreated depression -- about half of those who suffer from the disease -- face an estimated 15 percent greater likelihood of death by suicide.
Dr. Joseph Glenmullen, a Harvard Medical School clinical instructor in psychiatry and author of "Prozac Backlash," said expanding the warnings wouldn't scare off patients, but instead would allow them to make informed choices.
The FDA recently completed a review of 372 studies involving about 100,000 patients and 11 antidepressants, including Lexapro, Zoloft, Prozac and Paxil.
When the results were analyzed by age, it became clear there was an elevated though small and short-term risk for suicidal thoughts and behavior among adults 18 to 24, the FDA said in documents released ahead of yesterday's meeting of its psychopharmacologic drugs advisory committee.
The FDA's analysis of the multiple studies suggests an age-related shift in the risk of suicidal thoughts and behavior associated with treatment with the drugs. For instance, antidepressants seem to protect against suicidal thoughts and behavior in adults 30 and older, with the effect most pronounced in patients over 65.
The FDA said the increased risk could mean as many as 14 additional cases of suicidal thoughts or behavior in every 1,000 children treated with antidepressants. For adults 18 to 24, there could be four additional such cases per 1,000.
In May, GlaxoSmithKline and the FDA warned Paxil may raise the risk of suicidal behavior in young adults and added that to the drug's label.
"Anytime suicide is involved it is a tragic outcome. It is one of the things that keeps us motivated to search for better treatments because depression can be a fatal illness," GlaxoSmithKline spokeswoman Mary Anne Rhyne said.
On the Web: FDA on the use of antidepressants in children, adolescents and adults: www.fda.gov/cder/drug/antidepressants/default.htm