In June, 2005 the FDA issued warnings about drugs used to treat ADD and ADHD. The drugs in question are called methylphenidates this includes drugs like Ritalin, and Concerta. The concern that the drugs may produce psychiatric side-effects, including visual hallucinations, suicidal thoughts, aggression, violent behavior or psychotic behavior, prompted the action.

In February, 2005, Health Canada ordered Adderall XR (another ADD drug) off the market, after reports of sudden cardiac death in 20 patients. The FDA chose to merely put a warning on the label advising people with structural heart abnormalities to not take the drug. Another approved stimulant, pemoline (Cylert), has been restricted by the FDA to secondary use because it can cause liver failure.