Washington ? The Food and Drug Administration on Friday ordered that all antidepressants carry “black box” warnings that they “increase the risk of suicidal thinking and behavior” in children who take them.

Patients and their parents will be given medication guides that include the warning with each new prescription or refill.

Dr. Lester Crawford, acting FDA commissioner, said the agency based its decision on the “latest and best science.”

“We continue to believe, however, that these drugs provide significant benefits for pediatric patients when used appropriately,” he said.

The warning begins: “Antidepressants increase the risk of suicidal thinking and behavior … in children and adolescents with major depressive disorder and other psychiatric disorders.” Those risks must be balanced against clinical need, the label indicates in a warning surrounded by a black box, hence the “black box” designation.

The information guide for patients and their parents echoes those warnings.

The FDA’s action, which follows to the letter a recommendation of its advisers, was driven by data that showed that on average, 2 percent to 3 percent of children taking antidepressants have increased suicidal thoughts. Independent experts, working with Columbia University, based the finding on a review of data from 24 trials that involved more than 4,400 patients taking antidepressants. They found a greater risk during the first few months of treatment.

Crawford said suicides among youths decreased by 25 percent in the last decade, as antidepressant prescriptions to children soared. Children aged 1 to 17 now account for 7 percent of all antidepressant prescriptions.

The American Psychiatric Assn. expressed concern that the agency’s actions may lead to fewer prescriptions for patients most in need.