FDA

FDA adds seizure warning to carbidopa/levodopa labeling

March 23, 2026

FDA is requiring a new warning for all drug products containing carbidopa/levodopa stating that treatment may be associated with vitamin B6 deficiency and vitamin B6 deficiency–associated seizures. Updated labeling will direct clinicians to assess baseline vitamin B6 levels before initiation, monitor levels periodically during treatment, and supplement as needed. The action follows an FDA review identifying 14 reported cases of seizures in patients using carbidopa/levodopa, all involving daily levodopa doses >1,000 mg; seizures often didn't respond to standard antiseizure therapies but resolved after vitamin B6 administration. Two fatalities were reported in patients with documented vitamin B6 deficiency and poorly controlled seizures. Although reported cases involved oral and enteral (suspension) formulations, FDA concluded there is reasonable evidence supporting an association across carbidopa/levodopa–containing products (which also include a subcutaneous injection for continuous infusion).

Source:

(2026, March 20). FDA. FDA Is Requiring Warning about Vitamin B6 Deficiency and Associated Seizures for Drug Products Containing Carbidopa/Levodopa [PDF]. https://www.fda.gov/media/191605/download