The U.S. Food and Drug Administration (FDA) now requires medications containing carbidopa/levodopa to include a warning about the risk of vitamin B6 deficiency and related seizures.

These medications are commonly used to treat Parkinson’s disease. The new warning doesn’t mean the treatment works differently. It points out a risk that people with Parkinson’s and their caregivers should know about.

Research has linked carbidopa/levodopa treatment with low vitamin B6 levels in some people with Parkinson’s.

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🗳️ Have you had your vitamin B6 levels checked in the past year?

Yes, I was tested, and they found a B6 deficiency.

Yes, I was tested, and my vitamin B6 levels were in the normal range.

No, I haven’t been tested in the past year.

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A 2023 study found low B6 levels in nearly 45 percent of people using carbidopa/levodopa intestinal gel and 30 percent of those taking oral carbidopa/levodopa.

What Is Vitamin B6?

Vitamin B6 helps your body carry out many important functions, including supporting brain health, making neurotransmitters (chemical messengers), and forming red blood cells.

Carbidopa/levodopa can lower vitamin B6 levels in two ways:

• The body uses vitamin B6 to process levodopa.
• Carbidopa may attach to vitamin B6 and make it less active.

Over time, especially at higher doses, this may lead to a deficiency.

What the FDA Found

The warning is based on a review of 14 reported cases of vitamin B6 deficiency-related seizures in people taking carbidopa/levodopa. The FDA noted three patterns:

• All 14 cases involved higher doses, more than 1,000 milligrams per day.
• Seizures developed months to years after starting treatment.
• The seizures stopped after people received vitamin B6.

Although these cases appear to be uncommon, the FDA found enough evidence to require updated safety labeling.

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On MyParkinsonsTeam, people share their experiences with Parkinson's disease, get advice, and find support from others who understand.

Have you or a loved one had low vitamin B6 levels? Let others know in the comments below.