FDA adds vitamin B6 seizure warning to carbidopa/levodopa drugs

ByBrian “Weence” Bateman

The FDA now says all carbidopa/levodopa products need a warning about vitamin B6 deficiency and seizures. For people with Parkinson’s disease, the practical takeaway is to know the symptoms, avoid abrupt medicine changes, and ask a clinician whether vitamin B6 monitoring makes sense.

The FDA has added a new warning to all carbidopa/levodopa products used to treat Parkinson’s disease. The agency says these medicines can cause vitamin B6 deficiency, and in some cases that deficiency has been linked to seizures.

For patients, caregivers, and clinicians, the immediate takeaway is not to panic. It is to know the symptoms to watch for, and to talk with a clinician before making any changes to Parkinson’s treatment or starting vitamin supplements on your own.

What the FDA said

In a March 20, 2026 Drug Safety Communication, the FDA said it is requiring updated warning language for all drug products containing carbidopa/levodopa. The agency reviewed 14 cases of seizures linked to vitamin B6 deficiency in people taking these medicines. The FDA said higher doses of carbidopa/levodopa may increase the risk.

The agency also said clinicians should consider checking vitamin B6 levels before treatment begins, periodically during treatment, and again if symptoms of vitamin B6 deficiency appear. The FDA said vitamin B6 supplements may be needed in some patients, but only under medical guidance.

Who may be at higher risk

According to the FDA and MedlinePlus, the concern applies to carbidopa/levodopa products used by people with Parkinson’s disease. The FDA said higher doses may raise risk. MedlinePlus notes that the warning applies to common oral forms, including regular tablets, orally disintegrating tablets, extended-release tablets, and extended-release capsules.

The FDA’s review did not identify seizure cases tied to carbidopa/levodopa/entacapone products or the injectable carbidopa/levodopa product, though the agency noted that differences in use, approval dates, and dosing may help explain that finding.

Symptoms to watch for

The FDA said vitamin B6 deficiency can show up with seizures, but also with depression, confusion, inflammation of the lips, tongue, or skin, and nerve symptoms such as numbness, tingling, sharp pain, or muscle weakness. MedlinePlus echoes those warning signs and says people should seek emergency medical care if seizures occur.

These symptoms are not specific to vitamin B6 deficiency, which is one reason the FDA is urging follow-up with a clinician rather than self-treating.

What patients and caregivers can do

If you take carbidopa/levodopa, ask your clinician or pharmacist whether your vitamin B6 level should be checked and whether monitoring is appropriate over time. Ask whether any vitamin B6 supplement is needed, and if so, how much and for how long.

Keep an updated list of all prescription medicines, over-the-counter drugs, vitamins, and supplements. That can help clinicians spot interactions and avoid guesswork if new symptoms appear.

What not to do

Do not stop Parkinson’s medicine abruptly unless a clinician tells you to do so. Do not start vitamin B6 or other supplements on your own to try to fix symptoms without medical guidance. Changing treatment too quickly can create other risks, including worsening movement symptoms.

The bottom line

This FDA warning gives patients and prescribers a clear next step: watch for vitamin B6 deficiency, especially in people on higher doses or long-term therapy, and treat seizures or neurologic changes as symptoms that need prompt medical attention. For families and caregivers, the most useful action is to bring the question up at the next appointment rather than waiting for symptoms to become severe.

Sources

Editorial note: Weence articles are researched from cited public-health, medical, regulatory, journal, and reputable news sources and may be drafted with AI assistance. They are checked for source support, clarity, and safety guardrails before publication.

This article is for general informational purposes only and is not medical advice. Research findings can be early or incomplete, and health guidance can change. Always talk with a qualified healthcare professional about personal symptoms, diagnosis, medications, vaccines, screenings, or treatment decisions. If you think you may have a medical emergency, call emergency services right away.

Related

Brian “Weence” Bateman is a health and medical writer who covers public health updates, healthcare policy, and medical developments affecting communities across the United States. He works closely with dentists and healthcare providers and focuses on making complex medical information clear, accurate, and useful for everyday readers.