Iomeprol Injection and Levothyroxine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Levothyroxine
Iomeprol Injection
No brand names on record
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.
What happens
Reduced efficacy of thyroid therapy
Interaction Deep Dive
Avoid coadministration of iomeprol with thyroid hormones for up to 6 weeks post iomeprol as it may interfere with thyroid uptake of radioactive iodine (I-131 and I-123) and reduce therapeutic efficacy1.
Why it happens (mechanism)
Interference with thyroid uptake of radioactive iodine
Common questions
Can I take Iomeprol Injection and Levothyroxine together?
Reduced efficacy of thyroid therapy Always confirm with your pharmacist or prescriber before making any change.
How serious is the Iomeprol Injection and Levothyroxine interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Iomeprol Injection or Levothyroxine 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)
- Product Information: IOMERVU(TM) intravenous injection, intra-arterial injection, iomeprol intravenous injection, intra-arterial injection. Bracco Diagnostic Inc. (per FDA), Monroe Township, NJ, 2024. DailyMed
Keep reading about Levothyroxine
Keep reading about Iomeprol Injection
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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