The U.S. Food and Drug Administration (FDA) has notified application holders for all drug products containing carbidopa/levodopa that the Agency is requiring the addition of a warning, and corresponding revisions, to the prescribing information to state that these medications, approved to treat symptoms of Parkinson’s disease, can cause vitamin B6 deficiency and vitamin B6 deficiency-associated seizures. The warning directs health care professionals to evaluate baseline vitamin B6 levels prior to starting patients on treatment with carbidopa/levodopa therapies and periodically while on treatment and to supplement with vitamin B6 as necessary.