Drug Interaction Report

Thioridazine and Levodopa Oral Inhalation: Interaction Details

A pharmacist-reviewed analysis of the Thioridazine and Levodopa Oral Inhalation interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Thioridazine

No brand names on record
+

Levodopa Oral Inhalation

Inbrija Inbrija®
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Major
Potentially serious — often needs a change or close monitoring.
How we grade severity & evidence

Severity levels

  • Contraindicated: These should generally not be used together.
  • Major: Potentially serious — often needs a change or close monitoring.
  • Moderate: Can be significant — usually manageable with monitoring.
  • Minor: Usually limited clinical impact.

Evidence grades

  • Established: Well documented — supported by controlled studies or strong clinical data.
  • Probable: Good supporting evidence, though not definitively proven.
  • Suspected: Some evidence suggests this interaction, but it is not well established.
  • Possible: Limited or conflicting evidence; the interaction may occur.
  • Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.

Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.

Of 117 documented Thioridazine interactions, 49 are rated major — including this one.
Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.
Onset
rapid
Evidence
theoretical
Severity
Major

What happens

Reduce efficacy of levodopa (foslevodopa), an increased risk of exacerbating psychosis [or symptoms of Parkinson's disease: delusion, confusion, agitation, etc] and an increased risk of CNS depression

Interaction Deep Dive

Concomitant use of DOPamine D2 receptor antagonists and levodopa (foslevodopa), may reduce the effectiveness of levodopa (foslevodopa). Coadministration of foscarbidopa/foslevodopa with CNS depressants may also increase risk of CNS depression. Monitor patients for worsening of Parkinson's disease1.

Why it happens (mechanism)

Antagonism of DOPamine effects; additive CNS depression

Common questions

Can I take Thioridazine and Levodopa Oral Inhalation together?

Reduce efficacy of levodopa (foslevodopa), an increased risk of exacerbating psychosis [or symptoms of Parkinson's disease: delusion, confusion, agitation, etc] and an increased risk of CNS depression Always confirm with your pharmacist or prescriber before making any change.

How serious is the Thioridazine and Levodopa Oral Inhalation interaction?

It is rated major. Potentially serious — often needs a change or close monitoring.

How quickly could this interaction happen?

The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.

How strong is the evidence for this interaction?

The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.

Questions for your pharmacist

  • Does my dose of Thioridazine or Levodopa Oral Inhalation need adjusting while I take them together?
  • What symptoms should prompt me to call you or my prescriber right away?
  • Does the timing of my doses matter for this combination?
  • Is there a safer alternative to one of these medications for me?

References (1)

  1. Product Information: VYALEV(TM) subcutaneous injection, foscarbidopa and foslevodopa subcutaneous injection. AbbVie Inc (per FDA), North Chicago, IL, 2024. DailyMed
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Thioridazine

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All Thioridazine interactions (117)
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Levodopa Oral Inhalation

Keep reading about Levodopa Oral Inhalation

All Levodopa Oral Inhalation interactions (208) Levodopa Oral Inhalation drug information
Also serious with: Linezolid Methylene Blue Moclobemide Nialamide
Beyond drug–drug

These medications also interact with supplements

Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:

Thioridazine + Activated Charcoal American Hellebore Arsenic Cesium Ephedra Grapefruit Henbane Indian Snakeroot + 160 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.