Washington ? The antidepressant Paxil may raise the risk of suicidal behavior in young adults, GlaxoSmithKline and the Food and Drug Administration warned Friday in a letter to doctors.

The warning letter was accompanied by changes to the labeling of both Paxil and Paxil CR, a controlled-release version of the drug, also called paroxetine.

A recent analysis of clinical trial data on nearly 15,000 patients treated with both Paxil and dummy pills revealed a higher frequency of suicidal behavior in young adults treated with the drug, according to the letter.

The FDA reported that there were 11 suicide attempts – none resulting in death – among the patients given Paxil in the trials. Just one of the dummy pill patients attempted suicide.