The U.S. Food and Drug Administration (FDA) announced on Mar. 23 that certain Parkinson’s disease medications containing levodopa and carbidopa may increase the risk of seizures, especially in patients with vitamin B6 deficiency.
This safety warning is important for patients and healthcare professionals who rely on these common treatments for Parkinson’s disease. The FDA found that high doses of levodopa—over 1,000 mg per day—were associated with seizures in several reported cases.
According to the agency, a review identified 14 cases where patients taking products containing levodopa and carbidopa experienced seizures linked to low vitamin B6 levels. The FDA said, “All 14 cases of carbidopa/levodopa-linked seizures were detected through post-marketing surveillance or found in the medical literature, so there are likely additional cases about which we are unaware.” In these reports, two patients died after suffering poorly controlled seizures related to low vitamin B6 levels. Nine other patients improved after receiving vitamin B6 supplements.
The FDA noted that most affected individuals used oral formulations or enteral suspensions but warned that injectable forms or those combined with other compounds could also pose similar risks. “Biological plausibility suggests there may be a similar risk across all drug products containing carbidopa/levodopa,” the FDA wrote.
Manufacturers have been asked by the agency to update product labels with warnings about seizure risks related to vitamin B6 deficiency. Healthcare providers are advised by the FDA to monitor their patients’ vitamin B6 status before and during treatment, supplementing as needed.
Levodopa has been a mainstay therapy for Parkinson’s since its introduction in combination with carbidopa in 1975. Recent approvals such as AbbVie’s Vyalev offer new delivery methods for advanced disease, while companies like Novartis continue marketing combination therapies like Stalevo. Meanwhile, research into alternative therapeutic approaches is ongoing; Eli Lilly recently acquired Ventyx Biosciences for its investigational pipeline targeting inflammatory pathways implicated in Parkinson’s progression.
