The FDA has told drug makers to add a warning to all products containing carbidopa & levodopa – the most common medicines for Parkinson’s symptoms – because these drugs can lower vitamin B6 (pyridoxine) and have been linked to vitamin B6 deficiency–associated seizures. The agency reviewed reports and asked manufacturers to update prescribing information so health care professionals will check B6 levels before and during treatment and give supplements when needed.
What you should know
- Number of cases reviewed by FDA: 14 (13 from the FDA adverse event system and 1 from medical literature).
- All reviewed cases involved levodopa doses >1,000 mg/day; higher doses were linked to faster onset.
- Nine patients’ seizures stopped after vitamin B6 supplementation; two deaths were reported in patients with low B6 and uncontrolled seizures.
- The risk was seen across oral tablets, enteral suspensions, and infusion products that deliver carbidopa/levodopa or their prodrugs.
Why this happens
Levodopa is converted into dopamine in the brain. That conversion and the way carbidopa works can use up or block the active form of vitamin B6, lowering the body’s available B6. Low B6 can, in some people, lead to seizures – sometimes severe.
What patients and caregivers should do right now
- Do not stop your medication suddenly. Stopping levodopa abruptly can be dangerous.
- Ask your prescriber for a baseline vitamin B6 blood test and periodic checks if you’re on carbidopa/levodopa, especially at higher doses.
- Watch for warning signs: new seizures, confusion, numbness/tingling, mood changes, or unexplained weakness. Seek emergency care for any seizure.
- If your clinician recommends vitamin B6 supplementation, follow their dose and monitoring plan – in reported cases, supplementation resolved seizures.
What to ask your clinician
| Question to ask | Why it matters |
| “Can we check my vitamin B6 level now?” | Establishes a baseline. |
| “Is my levodopa dose above 1,000 mg/day?” | Higher doses were common in reported cases. |
| “Should I take vitamin B6 supplements?” | Some patients’ seizures stopped after B6 was given. |
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Source
FDA – Drug Safety Communication: FDA Is Requiring Warning about Vitamin B6 Deficiency and Associated Seizures for Drug Products Containing Carbidopa/Levodopa
https://www.fda.gov/media/191605/download?attachment . .