Atenolol and Iohexol: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 15, 2026 · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Atenolol
Iohexol
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.
Atenolol is a beta blocker you take for your heart or blood pressure. Iohexol is a contrast dye used during certain X-rays or CT scans. When you are on a beta blocker, two things can happen: your body may be a little more likely to have an allergic-type reaction to the dye, and if a reaction does happen, the usual rescue medicine (epinephrine) may not work as well.
This is a theoretical concern, not something that happens to everyone, and imaging teams deal with it all the time. The most important step is simple: tell the staff and your doctor that you take atenolol before any scan with contrast. They can watch you closely and be ready. Please do not stop your atenolol on your own.
Effect: Beta-adrenergic blockade (atenolol) may lower the threshold for and increase the severity of iohexol contrast hypersensitivity reactions, and may blunt the response to epinephrine used to treat anaphylaxis.
- Direction: Increased risk/severity of contrast reaction; reduced efficacy of epinephrine rescue (beta-receptor antagonism).
- Mechanism: Unknown/pharmacodynamic; beta blockade impairs compensatory beta-agonist response.
- Onset: Unspecified (peri-procedural).
- Evidence: Theoretical.
- Management: Document beta-blocker use pre-procedure; ensure resuscitation readiness. Reactions may require higher/repeated epinephrine and adjunctive glucagon for refractory bronchospasm/hypotension. Individualize continuation of atenolol with the prescriber.
What happens
Lower threshold for contrast reactions, increased risk of more severe contrast reaction, reduced efficacy when treating hypersensitivity reaction
Interaction Deep Dive
Caution is warranted when iohexol is given together with a beta-adrenergic blocking agent, since the combination raises both the likelihood and the intensity of hypersensitivity reactions. Beta blockers make contrast reactions more severe and reduce the threshold at which they occur. Furthermore, beta blockers diminish how well epinephrine works when it is administered to manage hypersensitivity reactions1.
Why it happens (mechanism)
Unknown
How to manage this interaction
This is manageable, and it is mostly about communication and monitoring.
- Speak up before your scan. Let the imaging staff and your doctor know you take atenolol so they can be prepared.
- Keep taking both as prescribed unless your care team tells you otherwise. Do not stop atenolol on your own.
- Expect closer monitoring during and after the contrast study. Teams routinely keep rescue medicines on hand.
- Ask your pharmacist or prescriber whether any change is right for your situation; any decision to hold or adjust atenolol should be individualized by your care team.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Atenolol and Iohexol together?
If you take atenolol, tell your imaging team and doctor before any scan that uses iohexol contrast, since a beta blocker can raise the risk and severity of contrast reactions and make rescue treatment less effective. Keep taking your medicine as prescribed and let your care team monitor you. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Atenolol and Iohexol 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 is the Atenolol and Iohexol interaction managed?
This is manageable, and it is mostly about communication and monitoring. Speak up before your scan. Let the imaging staff and your doctor know you take atenolol so they can be prepared. Keep taking both as prescribed unless your care team tells you otherwise. Do not stop atenolol on your own. Expect closer monitoring during and after the contrast study. Teams routinely keep rescue medicines on han… Management is individual — always follow your own care team's guidance.
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 Atenolol or Iohexol 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: OMNIPAQUE intravenous injection, iohexol intravenous injection. GE Healthcare Inc (per FDA), Marlborough, MA, 2017. DailyMed
Keep reading about Atenolol
Keep reading about Iohexol
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:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist