Updates on ADHD Stimulant Safety Warnings

Educational only — not medical advice.

In the mid-2000s, regulatory agencies in the U.S. and Canada issued several warnings about stimulant medications used for ADD and ADHD, including concerns about psychiatric side effects and rare cardiovascular complications.

Early FDA Concerns (2005)

In June 2005, the FDA warned that methylphenidate-based medications—including Ritalin and Concerta—could cause psychiatric side effects in some individuals. Reported reactions included:

  • Visual hallucinations

  • Suicidal thoughts

  • Aggression or violent behavior

  • Psychotic symptoms

These events were uncommon but serious enough to prompt stronger labeling and monitoring recommendations.

Adderall XR and Sudden Cardiac Events

In February 2005, Health Canada temporarily suspended Adderall XR after receiving reports of sudden cardiac death in 20 patients. Most cases involved individuals with underlying heart abnormalities or other significant risk factors.

The FDA reviewed the same data and chose not to withdraw the drug, but instead strengthened label warnings advising that people with structural heart defects should not use stimulant medications.

Pemoline (Cylert): Liver Toxicity Concerns

Another stimulant, pemoline (Cylert), had long been associated with cases of severe liver failure. By 2005, the FDA had restricted it to second-line use only, and by 2010 it was fully discontinued in the United States due to its risk profile.