Isoniazid and Levodopa interaction
Isoniazid and Levodopa: the Levodopa prescribing label flags this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Levodopa (Inbrija) label · effective 2026-01-16
INBRIJA is contraindicated in patients currently taking a nonselective monoamine oxidase (MAO) inhibitor (e.g., phenelzine and tranylcypromine) or who have recently (within 2 weeks) taken a nonselective MAO inhibitor.
INBRIJA is contraindicated in patients currently taking a nonselective monoamine oxidase (MAO) inhibitor or who have recently (within 2 weeks) taken a nonselective MAO inhibitor ( 4 , 7.1 )
Monoamine Oxidase (MAO) Inhibitors The use of nonselective MAO inhibitors with INBRIJA is contraindicated [see Contraindications (4) ] .
Dopamine D2 antagonists, isoniazid, and iron salts: May reduce the effectiveness of INBRIJA ( 7.2 , 7.3 )
Dopamine D2 Receptor Antagonists and Isoniazid Dopamine D2 receptor antagonists (e.g., phenothiazines, butyrophenones, risperidone, metoclopramide) and isoniazid may reduce the effectiveness of levodopa.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.