Drug interactions
Isoniazid + Levodopa
Severity: Moderate
Isoniazid and Levodopa: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Isoniazid may blunt the antiparkinsonian response to levodopa in some patients, leading to worsening motor symptoms. It can also add to the risk of hypertensive reactions through weak monoamine oxidase inhibition.
What this interaction means in plain words
Isoniazid and Levodopa can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Isoniazid belongs to Anti Bacterial; Levodopa belongs to Central Nervous System.
Why it happens
Isoniazid interferes with pyridoxine-dependent decarboxylation and has weak MAO-inhibiting activity, altering levodopa conversion and monoamine metabolism; the mechanism is not fully established.
What to do
Monitor for loss of motor control and for blood pressure elevation when isoniazid is started in a levodopa-treated patient. Adjust the levodopa dose if symptoms worsen.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Levodopa
- Isocarboxazid + Levodopa Contraindicated
- Levodopa + Phenelzine Contraindicated
- Levodopa + Phenelzine (nonselective MAOI) Contraindicated
- Levodopa + Procarbazine Contraindicated
- Levodopa + Tranylcypromine Contraindicated
- Amisulpride + Levodopa Major
Other interactions of Isoniazid
Frequently asked questions
Can I take Isoniazid with Levodopa?
MediHelp rates the interaction as moderate. Isoniazid and Levodopa can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Isoniazid may blunt the antiparkinsonian response to levodopa in some patients, leading to worsening motor symptoms. It can also add to the risk of hypertensive reactions through weak monoamine oxidase inhibition.
How serious is the interaction between Isoniazid and Levodopa?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for loss of motor control and for blood pressure elevation when isoniazid is started in a levodopa-treated patient. Adjust the levodopa dose if symptoms worsen.
What other medicines interact with Levodopa?
MediHelp also lists interactions of Levodopa with, for example, Isocarboxazid, Phenelzine, Phenelzine (nonselective MAOI). The full list is on the Levodopa page.
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