What the FDA labels say about taking them together
Foscarbidopa/foslevodopa and isoniazid
Foscarbidopa/foslevodopa's FDA label of March 19, 2026 names isoniazid in its drug interactions section; the isoniazid label PlainMeds reads does not name foscarbidopa/foslevodopa. The foscarbidopa/foslevodopa label: “Dosage adjustment of the antihypertensive drug may be needed. Dopamine D2 receptor antagonists and isoniazid may reduce the effectiveness of VYALEV.”
Check it at the source: the foscarbidopa/foslevodopa FDA label on DailyMed (effective March 19, 2026, AbbVie Inc.); the isoniazid FDA label on DailyMed (effective July 8, 2025, OMNIVIUM PHARMACEUTICALS LLC.).
What does the foscarbidopa/foslevodopa label say about isoniazid?
Foscarbidopa/foslevodopa label, drug interactionsDosage adjustment of the antihypertensive drug may be needed. ( 7.2 ) Dopamine D2 receptor antagonists and isoniazid may reduce the effectiveness of VYALEV.
Source: FDA drug label (Vyalev), AbbVie Inc., effective March 19, 2026 (SPL set 28e806e4-951c-40a9-9f0c-d0929caf054c), via openFDA; the full label on DailyMed
What does the isoniazid label say about foscarbidopa/foslevodopa?
Isoniazid's label (effective July 8, 2025) does not name foscarbidopa/foslevodopa in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (isoniazid), OMNIVIUM PHARMACEUTICALS LLC., effective July 8, 2025 (SPL set 35400f1d-fd25-4bfa-a382-ac390e21bf2e), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Foscarbidopa/foslevodopa | Isoniazid | |
|---|---|---|
| Labeled for | Parkinson's disease | n/a |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | n/a | $3.40 per tablet 300 mg tablet |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once