Welcome to the FDA Side Effects Update. This series is designed to keep you informed about the latest safety advisories and newly documented side effects of your medications. In this installment, we’re highlighting safety updates concerning drugs that treat symptoms of Parkinson’s disease: Carbidopa/Levodopa, Crexont, Dhivy, Duopa, Rytary, Sinemet, Stalevo, and Vyalev. Generic versions of these medications will have the same safety update
How to Read This Report+
This report is prepared using the most recent information posted in the SrLC database. It highlights recent safety labeling changes. It includes only newly reported side effects and safety information; additional side effects and warnings will appear on the drug label. Not all recent changes to the SrLC database or the label may be listed here. For all changes and the complete list of warnings and side effects, please click on the drug label link.
Each of the items (approval and update dates, drug names, etc.) contained in this report are obtained from the SrLC. The side effects and medication descriptions are simplified and made clearer, if needed. Sometimes, additional sources, like a medical dictionary, may be used to translate technical medical phrases. Other sources (company news, FDA press releases, etc.) may be used to learn about some label changes.
Updated Side Effect Warnings for Parkinson’s Medications
Medications containing the active ingredients carbidopa and levodopa are approved to treat symptoms of Parkinson’s disease, a progressive nervous system disorder. People with Parkinson’s disease experience a decline in dopamine, a brain chemical involved in movement and coordination. This can lead to symptoms such as tremors, muscle rigidity, slowed movement, and balance problems. Levodopa helps replenish dopamine levels in the brain, while carbidopa helps prevent levodopa from breaking down before it reaches the brain, making the treatment more effective. This combination helps manage movement-related symptoms of Parkinson’s disease and is also sometimes used to treat Parkinsonism, a group of Parkinson’s-like symptoms that can develop after encephalitis (brain inflammation), carbon monoxide poisoning, or manganese poisoning.
A March 2026 FDA Drug Safety Communication warns that medications containing carbidopa/levodopa may deplete levels of vitamin B6, potentially triggering seizures. Vitamin B6 plays an important role in red blood cell production, immune function, and normal brain and nerve activity. As part of its safety review, the FDA identified 14 seizure cases linked to carbidopa/levodopa in the FDA Adverse Event Reporting System, though the agency noted additional cases may have gone unreported. In the reported cases, the seizures resolved after patients received vitamin B6 supplementation.
The FDA advises that before and during carbidopa/levodopa treatment, vitamin B6 levels should be evaluated and monitored.
Symptoms of vitamin B6 deficiency can include seizures, depression, confusion, inflammation of the lips, tongue, and skin, as well as nerve damage that may cause numbness, tingling, sharp pain, or muscle weakness. Patients taking carbidopa/levodopa medications should speak with a healthcare professional about whether vitamin B6 supplementation is appropriate for them.
Crexont (carbidopa; levodopa) extended-release capsules
Initial FDA Approval: 1975 (active ingredient); 2024 (this product)
Side Effect Update Date: March 19, 2026
Medication Description: Treats Parkinson’s disease and Parkinson’s-like symptoms (parkinsonism) that can develop after encephalitis (brain inflammation), carbon monoxide poisoning, or manganese poisoning.
Updated Side Effects/Safety Information: A new warning notes that treatment with carbidopa/levodopa, particularly at higher doses, may contribute to low vitamin B6 levels. Seizures linked to severe vitamin B6 deficiency have been reported.
Vitamin B6 levels should be checked before and during treatment, with supplementation used if needed. Patients who experience symptoms of vitamin B6 deficiency — including depression, confusion, cracked or swollen lips or tongue, rash, low red blood cell counts, numbness, tingling, or weakness in the arms or legs — should contact their healthcare provider.
FDA Safety Announcement: Crexont Safety Label Change and Revised Drug Label and Drug Safety Communication
The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more.
Dhivy (carbidopa; levodopa) tablets
Initial FDA Approval: 1975 (active ingredient); 2021 (this product)
Side Effect Update Date: March 19, 2026
Medication Description: Treats Parkinson’s disease and Parkinson’s-like symptoms (parkinsonism) that can develop after encephalitis (brain inflammation), carbon monoxide poisoning, or manganese poisoning. Dhivy tablets are easily split, allowing incremental dosing.
Updated Side Effects/Safety Information: A new warning notes that treatment with carbidopa/levodopa, particularly at higher doses, may contribute to low vitamin B6 levels. Seizures linked to severe vitamin B6 deficiency have been reported.
Vitamin B6 levels should be checked before and during treatment, with supplementation used if needed. Patients who experience symptoms of vitamin B6 deficiency — including depression, confusion, cracked or swollen lips or tongue, rash, low red blood cell counts, numbness, tingling, or weakness in the arms or legs — should contact their healthcare provider.
FDA Safety Announcement: Dhivy Safety Label Change andRevised Drug Label andDrug Safety Communication
The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more.
Duopa (carbidopa; levodopa) enteral suspension
Initial FDA Approval: 1975 (active ingredient); 2015 (this product)
Side Effect Update Date: March 26, 2026
Medication Description: Treats motor fluctuations in people with advanced Parkinson’s disease. Duopa is administered as a 16-hour infusion through either a temporary feeding tube or a PEG-J tube placed directly into the abdomen.
Updated Side Effects/Safety Information: A new warning notes that treatment with carbidopa/levodopa, particularly at higher doses, may contribute to low vitamin B6 levels. Seizures linked to severe vitamin B6 deficiency have been reported.
Vitamin B6 levels should be checked before and during treatment, with supplementation used if needed. Patients who experience symptoms of vitamin B6 deficiency — including depression, confusion, cracked or swollen lips or tongue, rash, low red blood cell counts, numbness, tingling, or weakness in the arms or legs — should contact their healthcare provider.
FDA Safety Announcement: Duopa Safety Label Change and Revised Drug Label and Drug Safety Communication
The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more.
Rytary (carbidopa; levodopa) extended-release capsules
Initial FDA Approval: 1975 (active ingredient); 2015 (this product)
Side Effect Update Date: March 19, 2026
Medication Description: Treats Parkinson’s disease; also treats Parkinson’s-like symptoms (parkinsonism) that may develop after encephalitis (swelling of the brain), carbon monoxide poisoning, or manganese poisoning.
Updated Side Effects/Safety Information: A new warning notes that treatment with carbidopa/levodopa, particularly at higher doses, may contribute to low vitamin B6 levels. Seizures linked to severe vitamin B6 deficiency have been reported.
Vitamin B6 levels should be checked before and during treatment, with supplementation used if needed. Patients who experience symptoms of vitamin B6 deficiency — including depression, confusion, cracked or swollen lips or tongue, rash, low red blood cell counts, numbness, tingling, or weakness in the arms or legs — should contact their healthcare provider.
FDA Safety Announcement: Rytary Safety Label Change and Revised Drug Label and Drug Safety Communication
The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more.
Sinemet (carbidopa; levodopa) tablets
Initial FDA Approval: 1975
Side Effect Update Date: March 19, 2026
Medication Description: Treats Parkinson’s disease; also treats Parkinson’s-like symptoms (parkinsonism) that may develop after encephalitis (swelling of the brain), carbon monoxide poisoning, or manganese poisoning.
Updated Side Effects/Safety Information: A new warning notes that treatment with carbidopa/levodopa, particularly at higher doses, may contribute to low vitamin B6 levels. Seizures linked to severe vitamin B6 deficiency have been reported.
Vitamin B6 levels should be checked before and during treatment, with supplementation used if needed. Patients who experience symptoms of vitamin B6 deficiency — including depression, confusion, cracked or swollen lips or tongue, rash, low red blood cell counts, numbness, tingling, or weakness in the arms or legs — should contact their healthcare provider.
FDA Announcement: Sinemet Safety Label Change and Revised Drug Label and Drug Safety Communication
(Sinemet CR (brand name) has been discontinued, but the label was revised as the update will affect associated sustained release tablet generics: Sinemet CR Safety Label Change and Revised Drug Label)
The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more.
Stalevo (carbidopa; entacapone; levodopa) tablets
Initial FDA Approval: 1975 (active ingredient); 2003 (this product)
Side Effect Update Date: March 19, 2026
Medication Description: Treats Parkinson’s disease
Updated Side Effects/Safety Information: A new warning notes that treatment with carbidopa/levodopa, particularly at higher doses, may contribute to low vitamin B6 levels. Seizures linked to severe vitamin B6 deficiency have been reported.
Vitamin B6 levels should be checked before and during treatment, with supplementation used if needed. Patients who experience symptoms of vitamin B6 deficiency — including depression, confusion, cracked or swollen lips or tongue, rash, low red blood cell counts, numbness, tingling, or weakness in the arms or legs — should contact their healthcare provider.
FDA Safety Announcement: Stalevo Safety Label Change and Revised Drug Label and Drug Safety Communication (label change is same for each strength: 50, 100, 125, 150, 175, and 200 mg)
The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more.
Vyalev (foscarbidopa; foslevodopa) subcutaneous 24-hour infusion
Initial FDA Approval: 1975 (active ingredient); 2024 (this product)
Side Effect Update Date: March 19, 2026
Medication Description: Treats motor fluctuations in patients with advanced Parkinson’s disease
Updated Side Effects/Safety Information: A new warning that treatment with carbidopa/levodopa, the active metabolites of Vyalev, may contribute to low vitamin B6 levels. Seizures linked to vitamin B6 deficiency have been reported in patients taking carbidopa/levodopa, with symptoms resolving only after vitamin B6 was administered.
Vitamin B6 levels should be checked before and during treatment, with supplementation used if needed. Patients who experience symptoms of vitamin B6 deficiency — including depression, confusion, cracked or swollen lips or tongue, rash, low red blood cell counts, numbness, tingling, or weakness in the arms or legs — should contact their healthcare provider.
FDA Safety Announcement: Vyalev Safety Label Change and Revised Drug Label and Drug Safety Communication
The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more.