U.S. health officials on Friday ordered the makers of all antidepressants to include strong warnings explaining that the drugs increase the chances of suicidal behavior in some children and teens.

The Food and Drug Administration said the information, to be highlighted in a black box, must also state whether the drug has or has not been cleared for pediatric use. Only Eli Lilly and Co.‘s Prozac is FDA-approved for treating pediatric depression.

A black box is the strongest type of warning the United States requires for prescription drugs.

An FDA official told reporters that patients should see the label changes in the pharmacy in the next month or two.

The warning will stress the need to monitor the behavior of youths who start taking the medications. The chances of suicidal behavior appear greater during the first few months of treatment, the FDA said in a statement.

“The new warning language does not prohibit the use of antidepressants in children and adolescents. Rather, it warns of the risk of suicidal (behavior) and encourages prescribers to balance this risk with clinical need,” the FDA said.

The warnings will apply to all antidepressants “because the currently available data are not adequate to exclude any single medication from the increased risk,” the FDA said.

The agency said it is developing a pamphlet explaining the safety risks in patient-friendly language for pharmacists to distribute with each antidepressant prescription or refill.

A recent FDA analysis concluded two or three out of every 100 young people treated with antidepressants might face an elevated risk of suicidal thoughts or actions. In clinical trials of nine antidepressants, no child or teen actually committed suicide.

The FDA had been criticized for being slow to recognize the link between the drugs and suicidal thoughts and actions. One agency reviewer warned about the danger months ago, but top officials did not acknowledge a connection until September.

Top-selling antidepressants include Prozac, Pfizer Inc.‘s Zoloft, Wyeth’s Effexor and GlaxoSmithKline Plc’s Paxil.