Young adults starting to take antidepressant medication should be warned about the increased risk of suicidal thoughts and behaviour, the U.S. Food and Drug Administration recommended Wednesday.

The proposed labelling changes would, in effect, expand a current warning on the antidepressant medication.

The current language applies only to children and adolescents whereas the expanded warning would apply to adults 18-24 during the two months of treatment.

The proposed changes would also note that studies have not shown this increased risk in suicidal behaviour or thoughts among adults older than 24.

Nor would it say that adults 65 and older taking antidepressants have a decreased risk of suicidal thoughts and behaviour, the FDA said.

The recommended label changes stress that depression and some other serious psychiatric disorders are themselves the most important causes of suicide.

"Depression and other psychiatric disorders can have significant consequences if not appropriately treated. Antidepressant medications benefit many patients, but it is important that doctors and patients are aware of the risks," Dr. Steven Galson, the FDA's drugs chief, said in a statement.

The proposed expanded warnings were endorsed by FDA expert advisers.

In Canada, warnings on antidepressants already indicate that patients of all ages taking them may experience behavioural and-or emotional changes that may put them at increased risk of self-harm or harm to others.

In June 2004, Health Canada requested that manufacturers update their product monographs with the stronger warnings.

Experts have been split over the FDA's recommendations. While some argue that the label changes are long overdue, others say they could discourage patients who should be taking them.

Last month, authors of a new comprehensive analysis of antidepressants for children and teenagers said the benefits of treatment trump the small risk of increasing suicidal thoughts and behaviors in some patients.

The Journal of the American Medical Association study also found that risk is lower than what the FDA identified in 2004, the year the agency warned the public about the drugs' risks in children.

Some mental health experts suggested hesitance to try antidepressant medications was to blame for an increase in youth suicides after the warning was issued.

As of Wednesday, manufacturers of antidepressants have 30 days to submit their revised product labels and revised medication guides to the FDA for review.

For a list of products involved in the FDA's action, see this link.

With files from The Associated Press