The FDA panel voted 14 to 4 with 3 abstentions against adding the tougher warning because the panel said studies didn't show a high enough risk for suicidal behavior; however, the panel voted in favor of sending a medication guide to doctors detailing the risks of suicide with the drugs, The Wall Street Journal reported.

The FDA, which had previously said it wants to add the black-box warnings to more than 10 epilepsy drugs after studies showed their use led to a risk of suicidal behavior and thoughts, doesn't have to follow the panel's advice, but generally does.

A black-box warning is in bold type and is surrounded by a black border to make it stand out on the medication label. In addition, any advertising of products that carry black boxes must also include warning information as part of the advertisement, the journal said.

The agency has put warnings about suicidality -- suicide risk and suicidal behavior -- on about 35 drugs in the past four years.